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UNIVERSITY  OF  ILLINOIS 

Agricultural  Experiment  Station 


BULLETIN  No.  134 


THE  INSECT  PESTS   OF  CLOVER 
AND  ALFALFA 


BY  J.  W.  FOL8OM 


CONTENTS  OF  BULLETIN  No.  134 

PAGE 

Introduction 113 

Injury  to  Clover  by  Insects 113 

The  Failure  of  the  Seed  Crop 115 

Control  of  Clover  Insects 117 

Clover  Seed-midge,  Dasyneura  leguminicola 118 

Clover  Seed-chalcid,  Bruchophagus  funebris 125 

Clover  Seed-caterpillar,  Enarmonia  interstinctana 133 

Pea-louse,  or  Clover-louse,  Macrosiphum  pisi 138 

Clover  Leaf-weevil,  Phytonomus  punctatus. 155 

Clover  Root-borer,  Hylastinus  obscurus 164 

Clover  Hay-worm,  Hypsopygia  costalis 168 

Clover  Leaf-midge,  Dasyneura  trifolii 171 

Clover  Callipterus,  Callipterus  trifolii • 175 

Clover  Stem-borer,  Languria  mozardi 178 

Clover  Sitones,  Sitones  flavescens 184 

Clover-root  Mealy  Bug,  Pseudococcus  trifolii 189 

Literature 196 

General  Articles 196 

Lists  of  Species 196 


THE  INSECT  PESTS  OF  CLOVER  AND 
ALFALFA 

BY  J.  W.  FOLSOM,  ASSISTANT  PROFESSOR  OF  ENTOMOLOGY' 
UNIVERSITY  OF  ILLINOIS 

INTRODUCTION 

This  account  contains  a  large  amount  of  new  information  on  the 
most  injurious  of  the  clover  insects,  and  on  some  of  the  less  important 
species  as  well.  Unless  otherwise  indicated,  the  observations  were 
made  by  the  writer  during  three  summers  in  which  he  was  employed 
by  the  State  Entomologist,  Dr.  Stephen  A.  Forbes,  for  the  special  pur- 
pose of  studying  these  important  insects. 

The  volume  of  the  results  obtained — many  of  them  as  yet  unpub- 
lished— is  due  in  no  small  measure  to  the  help  of  an  assistant,  especially 
in  the  routine  work  of  the  insectary;  and  in  this  capacity  there  have 
served  at  one  time  or  another,  Messrs.  E.  V.  Bronson,  E.  O.  G.  Kelly, 
R.  L.  Webster,  and  J.  J.  Davis.  Their  names  appear  later  wherever 
their  personal  observations  have  been  used. 

The  present  account  contains  not  only  new  material,  but  also  every- 
thing of  importance- that  has  previously  appeared  in  our  literature  of 
the  subject.  The  literature  is  large,  but  the  greater  part  of  it  is  a  mass 
of  more  or  less  useful  repetition,  which  traces  back  to  a  few  sources. 
All  the  original  articles  are  cited  in  the  lists  of  references,  as  are  also 
the  more  useful  of  the  compiled  articles.  These  references,  tho  not 
voluminous,  are  comprehensive,  and  sufficient  to  guide  one  directly  to 
all  the  authentic  sources  of  information  on  each  subject  treated. 

Most  of  the  illustrations  were  drawn  for  the  State  Entomologist 
by  Miss  Charlotte  M.  Pinkerton,  Mr.  F.  Knab,  and  Mr.  W.  C. 
Matthews.  Several  electrotypes  were  obtained  from  the  Bureau  of 
Entomology  thru  the  courtesy  of  the  Chief,  Dr.  L.  O.  Howard. 

In  the  account  that  follows,  consideration  is  given  primarily  to  the 
insect  pests  of  red  clover,  and  secondarily  to  those  of  mammoth  clover, 
white  clover,  alsike,  and  alfalfa.  The  last-named  plant,  introduced 
into  Illinois  some  ten  years  ago,  is  cultivated  here  and  there  in  almost 
every  county,  and  has  been  adopted  as  a  food  plant  by  a  large  number 
of  the  red-clover  insects;  but  none  of  them  have  as  yet  injured  it  con- 
spicuously, so  far  as  the  writer  has  been  able  to  learn. 

INJURY  TO  CLOVER  BY  INSECTS 

A  field  of  red  clover  in  full  bloom  is  alive  with  insects.  Such  a 
profusion  of  insect  visitants,  both  as  regards  number  of  individuals  and 
number  of  species  at  one  and  the  same  time^  is  afforded  by  no  other 
plant  that  we  know  of,  with  the  possible  exception  of  alfalfa.  In  the 

113 


114  BULLETIN  No.  134  [April, 

clover  fields  of  the  university  farm  we  have  taken  two  hundred  species 
of  insects — not  all  of  them  injurious,  tho  more  than  half  of  them  feed 
on  the  plant.  Adding  to  these  the  other  species  that  have  been  listed 
as  feeding  on  clovers,  vetches,  and  alfalfa,  it  is  seen  that  these  plants 
are  food  for  more  than  two  hundred  different  kinds  of  insects.  A 
hundred  more  are  predaceous  or  parasitic  on  these  clover  insects,  or 
else  feed  on  animal  or  vegetable  matter  in  the  soil  of  the  clover  field. 

No  part  of  the  plant  escapes  attack.  The  roots  are  eaten  by  the 
larvae  and  the  beetles  of  the  root-borer,  as  well  as  by  those  of  half  a 
dozen  other  species,  and  are  drained  of  their  sap  by  the  mealy  bug. 
The  stem  is  hollowed  out  by  the  common  stem-borer.  Both  the  stems 
and  the  leaves  are  pierced  by  many  hemipterous  insects,  especially 
aphids  and  jassids,  and  are  eaten  by  a  great  variety  of  caterpillars, 
beetles,  and  grasshoppers,  as  are  also  the  heads  of  the  flowers.  The 
ovule  is  destroyed  by  the  maggot  of  the  seed-midge,  and  the  developing 
seed  is  eaten  out  by  the  seed-chalcid.  Even  clover  hay  is  the  special 
food  of  a  certain  caterpillar,  hence  called  the  clover  hay-worm. 

Some  of  the  insects  of  the  clover  field  are,  of  course,  beneficial. 
Such  are  those  that  pollenize  the  flowers, — bumblebees  and,  to  some 
extent,  honey-bees, — as  well  as  those  that  act  as  checks  on  the  injurious 
insects. 

Most  of  the  clover  insects  are  not  limited  to  clover,  but  have  other 
food  plants  as  well.  The  seed-midge  and  the  seed-caterpillar  are,  how- 
ever, confined  to  the  clovers,  and  the  seed-chalcid  to  clovers  and  alfalfa, 
so  far  as  known.  The  root-borer  is  said  to  eat  peas  as  well  as  clover. 
The  hay-worm  has  been  found  only  on  hay  as  yet,  but  the  moth  has 
been  raised  from  masses  of  dead  grape  leaves  taken  in  a  vineyard.  The 
leaf-weevil  is  reported  from  beans  and  timothy,  as  well  as  clover  and 
alfalfa.  The  clover-louse  has  been  a  pest  of  the  worst  kind  on  peas 
and  has  a  long  list  of  food  plants.  Of  the  less  important  clover  in- 
sects, a  few  have  no  other  food  plant;  but  the  majority  can  easily  main- 
tain their  existence  when  no  clover  is  at  hand. 

In  Illinois,  where  alfalfa  is  a  recent  introduction,  its  insects  are 
essentially  the  same  as  those  of  red  clover,  and  it  has  as  yet  no  insects 
peculiar  to  itself.  The  leaf-weevil,  seed-chalcid,  and  root-borer  feed 
on  alfalfa,  but  not  enough  to  have  done  any  damage  up  to  the  present 
time.  Even  the  numerous  caterpillars,  beetles,  and  grasshoppers  that 
eat  the  foliage  have  not  yet  injured  this  newly  introduced  plant  to  any 
great  extent.  An  insect  that  eats  a  few  alfalfa  leaves  is  not  necessarily 
inflicting  permanent  injury  upon  the  plant;  for,  up  to  a  certain  point, 
the  plant  is  injured  by  leaf -eating  insects  no  more  than  a  fruit  tree  is 
injured  by  pruning.  Red  clover,  also,  is  such  a  vigorous  plant  that  it 
easily  withstands  or  repairs  injuries  of  an  ordinary  kind.  Thus  in 
April,  1907,  25  to  50  percent  of  the  new  leaves  of  red  clover  were 
frozen  and  killed  in  this  region,  but  the  hay  crop  was  as  good  as  ever. 
The  temporary  damage  was  far  greater  than  that  ordinarily  inflicted 
by  the  miscellaneous  clover  insects — leaving  out  of  consideration  the 
seven  pests  named  in  the  previous  paragraph. 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  115 

The  combined  efforts  of  all  the  insects,  however,  are  sufficient  to 
reduce  the  hay  crop  materially  every  year.  Aside  from  the  occasional 
conspicuous  injury,  there  is  every  year  a  steady  drain  on  the  plant 
thru  the  attacks  of  insects.  This  annual  drain  is  not  noticed  for  the 
very  reason  that  it  occurs  every  year.  If  we  could  keep  all  the  insects 
out  of  the. clover  field,  we  should  get  more  hay.  If  we  could  exclude 
all  except  the  bumblebees  and  the  honey-bees,  we  should  undoubtedly 
get  an  immense  increase  in  the  yield  of  seed. 

Those  who  raise  clover  seed  on  a  commercial  scale  owe  their  suc- 
cess to  methods  which  operate  chiefly  against  the  insect  enemies  of  the 
seed — whether  the  growers  are  aware  of  it  or  not.  Under  the  same 
conditions  of  soil  and  climate,  one  man  is  able  to  get  a  good  crop  of 
seed  and  his  neighbor  is  not.  The  reasons  for  this  are  chiefly  entomo- 
logical, as  appears  in  these  pages. 

THE   FAILURE  OF  THE   SEED   CROP 

Many  farmers  do  not  attempt  to  raise  their  own  clover  seed. 
Those  who  do,  get  more  or  less  of  a  crop  according  to  circumstances. 
Here  in  the  black  soil  of  the  corn  belt,  1  */2  bushels  of  seed  per  acre  is 
about  the  average  yield  for  red  clover  (Trifolium  pratense)  ;  the  soil 
is  not  the  best  possible  for  clover ;  frequently  too  little  seed  is  sown ; 
generally  the  oats  and  the  wheat  are  regarded  as  of  more  importance 
than  the  clover;  and  always  the  seed  insects  ravage  the  crop  unless 
certain  precautions  are  taken.  In  DeKalb  county  the  soil  is  better 
adapted  to  clover,  and,  tho  the  winter  conditions  are  now  and  then  a 
little  severe  for  the  plant,  the  farmer  expects  to  get  about  five  bushels 
of  seed  to  the  acre  by  cutting  the  hay  crop  early.  Under  the  most 
favorable  conditions,  red  clover  has  yielded  eight  bushels  per  acre;  I 
have  found  records  of  nine,  but  the  more  authentic  accounts  name  no 
more  than  eight. 

Many  influences,  more  or  less  important,  combine  to  reduce  the 
crop  of  seed.  Adverse  mechanical  or  chemical  conditions  of  the  soil, 
or  unfavorable  conditions  of  the  weather,  may  prevent  the  plant  from 
flowering  properly.  With  good  conditions  of  soil  and  weather,  the  gen- 
eral health  of  the  plant  may  be  impaired  by  fungous  diseases  of  several 
kinds  or  by  insects,  particularly  the  root-borer,  the  leaf-weevil,  and  the 
clover-louse ;  their  devastations  cause  the  heads  to  flower  unevenly  and 
imperfectly,  and  prevent  the  formation  of  a  large  number  of  heads  in 
the  crop  directly  attacked  by  them. 

These  injuries,  due  to  influences  that  affect  primarily  the  general 
health  of  the  plant  and  secondarily  the  seed,  are  easily  referable  to 
their  respective  causes.  The  worst  injuries  to  the  seed  are  more  in- 
sidious in  their  nature,  and  are  caused  by  insects.  These  injuries  are 
of  three  classes :  ( 1 )  those  of  a  negative  kind,  due  to  lack  of  pollina- 
tion; (2)  the  positive  injuries  due  to  miscellaneous  insects  that  eat 
clover  heads  in  an  incidental  way;  (3)  the  positive  injuries  caused  by 
insects  that  feed  solely  upon  clover  seeds  or  florets.  The  first  two 
groups-are  relatively  unimportant  in  comparison  with  the  last. 


116  BULLETIN  No.  134  [April, 

1.  We  should  have  no  red  clover  seed  at  all  were  it  not  for  the 
operations  of  the  bumblebees  and,  secondarily,  of  the  longer-tongued 
honey-bees  (those  of  Italian  races),  for  red  clover  is  incapable  of  self- 
pollination.     The  importance  of  the  bumblebee  in  the  pollination  of  red 
clover  is  so  well  established  as  to  need  no  discussion.     That  of  the 
honey-bee,  however,  is  not  sufficiently  recognized.    The  honey-bee  pol- 
lenizes  red  clover  to  some  extent,  even  tho  its  tongue  is  two  millimeters 
shorter  than  the  average  corolla  tube.    A  field  of  red  clover  is  always 
thronged  with  honey-bees  if  any  of  them  are  being  kept  within  a  mile 
or  two  of  the  place ;  and  these  bees  secure  nectar  from  flowers  that  are 
undersized,  especially  in  times  of  drought,  when  most  of  the  flowers 
are  smaller  than  usual ;  also  from  flowers  that  secrete  a  copious  amount 
of  nectar.     Furthermore,  the  honey-bees,  in  their  attempts  to  get  the 
nectar,  go  thru  the  motions  of  pollination  whether  they  get  any  nectar 
or  not,  as  I  have  ascertained. 

The  lack  of  seed  in  the  June  or  early  July  crop  is  generally  at- 
tributed to  the  lack  of  bumblebees  at  that  time,  and  rightly  so,  in  my 
opinion.  Occasionally,  however,  the  farmer  is  surprised  to  find  a  pay- 
ing amount  of  seed  in  his  first  crop.  This  happened  in  Illinois  in  1906 
and  again  in  1907  in  various  counties  in  all  parts  of  the  state,  as  I  have 
learned  from  correspondence  and  from  personal  conversation  with 
clover  growers  at  the  State  Farmers'  Institute  and  elsewhere.  This 
early  seed  ran  one  to  two  bushels  to  the  acre ;  some  of  it  was  put  on 
the  market  in  Quincy,  111.  Only  two  farmers  offered  any  explanation 
for  the  production  of  clover  seed  at  this  untimely  season,  and  they  laid 
it  to  a  "miller"  that  pollenized  the  flowers  by  night  unobserved.  This 
miller  I  am  not  acquainted  with ;  perhaps  the  honey-bees  pollenized  the 
flowers. 

Ordinarily,  however,  we  do  not  expect  to  get  seed  from  the  June 
crop ;  and  by  midsummer  there  are  always  enough  bees  to  pollenize  the 
flowers.  The  failure  of  the  seed  crop  need  not  be  laid  to  lack  of  pol- 
lination as  yet.  In  the  future,  if  bumblebees  are  constantly  destroyed 
we  may  be  obliged  to  cultivate  them  artificially — and  this  can  be  done, 
if  necessary  for  the  welfare  of  clover.  The  indiscriminate  killing  of 
bumblebees  should  be  stopped.  They  are  the  best  friends  of  the  clover 
grower. 

2.  The  seed  crop  is  diminished  to  some  extent  by  various  grass- 
hoppers,  beetles,    and   caterpillars   that   eat   the    blossoms    here    and 
there,  and  sometimes  the  green  seeds.     They  prevent  pollination  and 
destroy  developing  seeds  in  some  measure,  but  can  scarcely  be  guarded 
against,  and  need  no  special  consideration. 

3.  There  are,  however,  three  insects  that  must  be  guarded  against 
if  one  wishes  to  raise  a  good  crop  of  seed.    These  are  the  seed-midge, 
the  seed-chalcid,  and  the  seed-caterpillar.     When  clover  blooms  well, 
and  there  is  good  weather,  the  failure  of  the  seed  crop  is  to  be  charged 
to  these  three  insects,  the  last  of  them  being  the  least  to  blame,  as  a 
rule.     All  three  can  be  controlled  by  simple  methods  described  later, 
the  most  important  of  these  being  the  early  cutting  of  the  hay  crop. 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  117 

It  seems  curious  at  first  sight  that  an  unusually  large  yield  of 
seed  should  follow  the  ravages  of  the  clover  leaf-weevil.  Yet  this  has 
occurred  in  several  instances.  Webster  observed  the  fact  in  Ohio.  The 
explanation  is  simple,  however,  in  my  opinion,  for  the  weevil,  when  a 
pest,  consumes  enough  leaf  tissue  to  delay  the  growth  of  the  plant 
materially,  taking  the  seed  crop  out  of  the  reach  of  its  worst  insect 
enemies.  The  result  is  the  same  as  that  obtained  by  the  seed  growers 
who  pasture  the  clover  in  May  or  early  June. 

Early  pasturing  or  cutting  is  the  secret  of  a  good  seed  crop,  as  the 
growers  in  New  York,  Ohio,  Michigan,  Canada,  and  elsewhere  have 
found.  The  reason  for  the  practice  is  not  universally  known,  however*, 
as  is  evident  from  the  inadequate  explanations  that  have  appeared  now 
and  then  in  agricultural  publications.  For  example,  Shaw  says  (Clo- 
vers, etc.,  p.  103),  "Experience  has  shown,  further,  that,  as  a  rule,  bet- 
ter crops  of  clover  seed  may  be  obtained  from  clover  that  has  been 
pastured  off  than  from  that  which  has  been  mown  for  hay,  although  to 
this  rule  there  are  some  exceptions.  This  arises,  in  part,  from  the 
fact  that  the  energies  of  the  plant  have  been  less  drawn  upon  in  pro- 
ducing growth,  and,  therefore,  can  produce  superior  seed  heads  and 
seed,  and  in  part  from  the  further  fact  that  there  is  usually  more 
moisture  in  the  soil  at  the  season  when  the  plants  which  have  been 
pastured  off  are  growing.  There  would  seem  to  be  some  relation  be- 
tween the  growing  of  good  crops  of  clover  seed  and  pasturing  the 
same  with  sheep."  The  fact  is  that  pasturing  gives  a  good  seed  crop 
for  the  reason  that  it  delays  the  heading  of  the  plant  until  a  time  when 
the  seed-midges  and  seed-chalcids  are  no  longer  on  the  wing  and  laying 
eggs.  When  precautions  are  not  taken  against  these  pests,  they  can  be 
counted  upon  every  year  to  destroy  most  of  the  clover  seed.  In  this 
region  the  midge  and  the  chalcid  eat  from  50  to  75  percent  of  the  red- 
clover  seed  every  year  without  hindrance.  The  farmer  gets  only 
what  the  insects  leave.  If  he  gets  two  bushels  of  seed  to  the  acre,  the 
insects  have  already  eaten  from  two  to  six  bushels  off  the  same  acre. 

CONTROL  OF  CLOVER  INSECTS 

The  insect  pests  of  clovers  are  but  seven,  and  they  are  within  our 
control  if  we  choose  to  control  them.  Moreover,  they  can  be  controlled 
by  means  that  interfere  little,  if  any,  with  usual  farm  practice;  and  the 
methods  of  control  do  not  conflict  with  one  another,  but  are  essentially 
the  same  for  all  the  clover  pests, — referring  especially  to  those  of  red 
clover. 

The  worst  of  these  to  deal  with,  where  it  occurs  injuriously,  is  the 
root-borer.  If  it  is  very  destructive  in  spring,  plow  the  clover  under, 
for  this  insect  has  quite  its  own  way.  The  other  pests  can  be  disposed 
of  without  sacrificing  the  plant. 

If  the  hay  crop  is  threatened  seriously  in  spring  by  the  leaf-weevil 
or  the  clover-louse,  pasture  it  or  clip  it  back  in  May;  otherwise,  cut 
the  hay  as  early  as  possible,  in  order  to  insure  a  good  second  growth. 
Usually,  however,  these  two  insects  are  subdued  by  natural  agencies, 
in  spite  of  their  abundance. 


118  BULLETIN  No.  134  [April, 

To  get  rid  of  the  worst  of  the  seed  insects,  pasture  or  clip  back  in 
May  or  early  June ;  or  else  cut  the  hay  as  soon  as  possible — as  soon  as 
it  is  fresh  in  bloom,  or  earlier. 

Cut  red  clover,  or  pasture  it  lightly,  in  the  latter  part  of  the  first 
season,  as  this  goes  far  to  reduce  the  number  of  insect  pests  in  the 
same  field  the  second  year,  and  does  not  injure  the  clover  if  done 
intelligently.  Destroy  volunteer  clover,  which  is  a  rich  nursery  for  all 
kinds  of  clover  insects.  It  can  be  cut  most  conveniently  with  the  rest 
of  the  clover — twice  a  year. 

Do  not  permit  red  clover  to  run  for  more  than  two  years  in  this 
region,  where  it  is,  for  agricultural  purposes,  a  biennial. 


CLOVER   SEED-MIDGE 

Ddsyneura  leguminicola  Lint. 

(Cecidomyia  leguminicola) 

This  widely  distributed  pest,  abundant  in  clover  fields,  prevents 
the  formation  of  seed.  At  the  time  of  blossoming,  the  florets  affected 
by  this  insect  remain  for  the  most  part  green  and  undeveloped,  and 
their  ovaries  are  hollowed  out  and  empty,  or  else  contain  each  a  small 
orange,  pink,  or  whitish  maggot.  Having  entered  the  flower-bud,  the 
maggot  consumes  the  fluid  contents  of  the  ovary  before  the  bud  has  a 
chance  to  open.  Hence  the  term  bud-midge  would  be  even  more  ap- 
propriate for  this  insect  than  that  of  flozver-midge — recently  proposed 
by  Webster. 

The  maggots  develop  into  delicate  little  red-bodied  flies,  which  are 
so  small  as  easily  to  escape  observation,  altho  they  are  very  abundant 
in  clover  fields  at  certain  periods  of  the  year. 

Distribution. — The  clover  seed-midge  has  been  reported  as  de- 
structive in  Vermont,  New  York,  New  Jersey,  Pennsylvania,  Delaware, 
the  District  of  Columbia,  Virginia,  Ohio,  Illinois,  Iowa,  Michigan,  Wis- 
consin, and  Nebraska,  and  doubtless  occurs  in  other  states  in  which 
clovers  are  grown.  It  does  great  damage  in  the  province  of  Ontario, 
Canada,  and,  according  to  Miss  Ormerod,  is  also  found  in  England. 
In  Illinois,  the  pest  was  observed  as  long  ago  as  1878  or  1879  (Fif- 
teenth Rep.  State  Ent.  111.,  p.  3). 

Food  Plants. — The  chief  food  plant  of  the  species  is  red  clover, 
but  white  clover  also  is  affected.  The  published  statement  that  alsike 
clover  is  exempt  from  attack  is  incorrect,  the  writer  having  reared  the 
midge  from  alsike.  This  clover  is  not  badly  infested,  however,  proba- 
bly because  it  forms  its  heads  three  weeks  later  than  red  clover,  at  a 
time  when  there  are  but  few  seed-midges  on  the  wing.  For  the  same 
reason  mammoth  clover  ought  to  escape  severe  attack,  and  such  is  said 
by  one  writer  to  be  the  case  (Insect  Life,  Vol.  V.,  p.  74).  An  implica- 
tion to  the  contrary,  however,  is  found  in  another  publication  (Bull. 
116,  Mich.  Agr.  Exper.  Station,  p.  55).  I  have  had  no  personal  experi- 
ence with  the  midge  on  mammoth  clover,  but  would  point  out  the  pos- 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  119 

sibility  that  the  injury  in  Michigan  was  done  by  the  seed-chalcid  rather 
than  by  the  seed-midge. 

Alfalfa  is  not  yet  known  to  be  a  food  plant  of  this  insect. 

Descriptions. — The  egg  is  barely  visible  to  the  naked  eye.  It  is 
elliptico-cylindrical  in  form,  at  most  0.3  mm.  long  and  0.075  mm.  broad, 
with  the  shell  smooth  and  transparent.  The  color  is  at  first  a  uniform 
watery  yellow,  but  soon  an  internal  orange  spot  appears,  and  finally 
the  egg  becomes  orange  thruout. 

The  larva  (PI.  I.,  Fig.  1)  is  a  footless  maggot,  orange-red,  pink,  or 
almost  white,  2.3  mm.  long  and  one  third  as  broad,  when  full  grown, 
with  the  surface  of  the  skin  minutely  granulate.  It  has  thirteen  seg- 
ments behind  the  head,  and,  like  other  cecidomyiid  larvae,  bears  nine 
pairs  of  respiratory  tubercles,  situated  respectively  on  segment  2  and 
segments  5  to  12  inclusive.  All  these  tubercles  are  lateral  in  position 
excepting  the  first  and  the  last  pairs,  which  are  dorsal  and  posterior  on 
their  respective  segments.  A  peculiar  organ  known  as  the  sternal 
spatula  may  be  detected  lying  against  the  ventral  face  of  segment  2, 
and  the  form  of  this  organ  (PI.  I.,  Fig.  2),  while  subject  to  some  varia- 
tion, is  sufficiently  characteristic  to  distinguish  this  larva  from  that  of 
the  clover  leaf-midge,  the  only  other  insect  with  which  it  is  likely  to 
be  confused. 

The  cocoon,  made  by  the  larva,  is  oval  in  form,  2  mm.  long,  and 
composed  of  silken  threads.  It  is  difficult  to  find  out-of-doors  owing 
to  its  being  covered  with  particles  of  dirt.  The  pupa,  described  in 
some  detail  by  Comstock,  is  pale  orange,  with  brown  eyes,  a  pair  of 
short  conical  tubercles  on  the  front  of  the  head,  and  a  rather  long  horn 
near  the  base  of  each  wing;  the  antennal  sheaths  of  the  cast  pupal 
skin  curve  outward  like  the  handles  of  an  urn. 

The  appearance  of  the  female  midge  is  well  shown  in  Figure  3, 
Plate  I.  When  on  the  wing,  she  is  nothing  but  a  filmy  speck,  that 
easily  eludes  the  vision.  After  alighting,  her  red  abdomen  and  long 
threadlike  legs  catch  the  eye.  Under  the  microscope,  the  head  is  seen 
to  be  black,  and  the  antennae  yellowish  red,  with  sixteen — or  even  sev- 
enteen-— sessile  segments.  The  sides  of  the  thorax  are  reddish  brown ; 
above,  most  of  the  thorax  is  black,  but  two  small  posterior  lobes  are 
brownish  red;  the  halteres  are  reddish  yellow.  The  wings  are  trans- 
parent, closely  set  with  short,  curved,  dusky  hairs,  and  strongly  fringed 
posteriorly  with  long  paler  hairs.  Legs  slender,  reddish  brown,  the 
segments  becoming  darker  distally.  The  abdominal  segments  1  to  6 
are  salmon-red  above,  mixed  with  yellowish  beneath ;  dorsally  each  of 
these  segments  is  banded  with  black  scalelike  hairs,  which  rub  off 
easily.  Segments  7  to  10  of  the  abdomen  form  the  pale  yellow 
ovipositor.  The  insect,  with  ovipositor  retracted,  is  1.8  to  2  mm.  in 
length,  and  with  the  ovipositor  extruded,  6.2  mm.  The  antennae  are 
0.8  mm.  in  length. 

The  male  resembles  the  female,  but  bears  a  pair  of  conspicuous 
clasping  organs  at  the  end  of  the  abdomen  and  has  but  fifteen  antennal 
segments,  all  but  the  first  two  of  which  are  pediceled. 


120  BULLETIN  No.  134  [April, 

We  have  no  other  midge  that  I  know  of  in  a  red  clover  field  that 
may  be  mistaken  for  the  seed-midge,  tho  in  Europe  the  leaf-midge  was 
originally  described  from  red  clover.  Both  midges  affect  white  clover, 
however,  but  can  be  distinguished  by  the  characters  given  on  page  172. 

Life  History. — In  central  Illinois,  the  clover  seed-midge  winters 
as  a  full-grown  larva,  or  as  a  pupa,  in  the  soil  of  the  clover  field  or  in 
dead  clover  heads.  A  few  warm  days  and  a  little  rain  bring  the  larvae 
to  the  surface  of  the  ground  a  few  days  after  the  red  clover  has 
started  on  its  second  year's  growth.  Thus  in  1907,  in  Urbana,  the 
first  new  leaves  of  red  clover  appeared  March  19 — a  little  earlier  than 
usual — and  the  orange-colored  larvae  of  the  midge  were  found  on  the 
ground  from  March  25  to  April  4,  inclusive,  being  most  numerous 
March  30  and  April  2.  They  are  by  no  means  abundant,  however,  at 
this  time  in  a  clover  field  of  the  second  year,  and  would  not  be  present 
at  all  but  for  the  precocious  development  of  some  clover  heads  during 
the  preceding  season.  Some  of  these  larvae  make  a  cocoon  and  some 
do  not.  In  either  event  the  larva  contracts  in  length  and  its  integument 
hardens  and  becomes  duller  in  color,  forming  a  puparium,  within  which 
the  pupa  develops.  One  larva,  found  March  25,  1907,  made  a  cocoon 
March  30,  from  which  a  female  midge  emerged  April  12  or  13.  A 
second  larva,  taken  March  30,  formed  a  cocoon  April  2  and  gave  a 
female  fly  April  21.  Both  of  these  flies  were  reared  indoors,  it  should 
be  said.  Out-of-doors,  midges  were  not  found  until  May  15,  but  were 
common  May  23  (at  which  date  oviposition  was  in  progress)  and  at- 
tained their  maximum  numbers  May  30.  This  season  was  a  late  one, 
however,  owing  to  continuous  cold  weather  in  April,  and  in  the  years 
1903  to  1906  inclusive  the  dates  of  maximum  abundance  were  May  24 
and  25,  the  time  when  young  green  clover  heads  also  were  most  numer- 
ous. The  larvae  work  in  the  heads  during  June  and  the  first  week  of  July, 
and  leave  the  heads  when  full  grown  and  go  to  the  ground  to  pupate. 
Our  earliest  date  for  the  emergence  of  larvae  from  the  heads  is  June  20. 
Most  of  the  larvae  emerge  about  June  30,  tho  not  a  few  wait  as  late  as 
July  8.  The  pupal  period  at  this  time  is  three  weeks  or  more,  and  the 
flies  of  the  second  generation  are  most  abundant  in  the  last  week  of 
July  and  the  first  two  weeks  of  August,  tho  scattering  individuals 
emerge  at  almost  any  other  time  between  the  middle  of  July  and  the 
first  of  September.  The  egg  period  in  early  August  is  three  days, 
varying  a  few  hours,  more  or  less,  according  to  temperature.  Most  of 
the  damage  to  the  seed  crop  is  done  during  the  last  two  weeks  of  Au- 
gust and  the  first  two  weeks  of  September,  when  the  larvae  are  most 
numerous  in  clover  heads.  Most  of  these  larvae  pass  the  winter  as 
larvae  or  pupae,  to  emerge  as  flies  the  following  May.  A  few  larvae, 
liowever,  attain  their  growth  early  enough  to  produce  flies  in  early  Sep- 
tember or  even  later,  out-of-doors.  Under  the  sheltered  conditions  of 
the  insectary,  but  without  artificial  heat,  flies  appeared  as  late  as  Octo- 
ber 10;  and  in  a  warm  room  flies  will  emerge  from  clover  sod  thruout 
the  winter.  It  appears  that  the  few  flies  of  late  September  do  not 
succeed  in  propagating  their  kind  in  this  latitude,  owing  to  the  direct 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  121 

effect  of  frost  on  the  flies,  but  especially  to  the  death  of  green  clover 
heads  before  any  larvae  therein  can  attain  their  growth.  It  is  possible, 
however,  that  flies  of  early  September  produce  larvae  capable  of  sur- 
viving the  winter. 

Thus  there  are  in  central  Illinois  two  full  broods  of  the  seed- 
midge  each  year  and  a  feeble  third  generation  of  flies,  which  belong 
essentially  to  the  May  brood  of  the  next  year.  In  the  literature  we 
find  that  maggots  of  the  seed-midge  emerged  in  immense  numbers 
from  clover  heads  in  Washington,  D.  C,  on  May  23,  1880.  This  date 
would  be  one  month  too  early  for  such  an  occurrence  in  this  part  of 
Illinois,  where  May  23  is  ordinarily  the  time  of  maximum  abundance 
of  the  first  generation  of  flies. 

Habits. — The  eggs  are  laid  always  in  green  flower-heads,  and 
chiefly  during  the  warmer  part  of  the  day.  With  the  aid  of  a  haml 
lens,  the  process  of  oviposition  can  be  observed,  the  female  being  fre- 
quently too  busy  to  pay  any  attention  to  slight  interruptions.  The  last 
four  segments  of  the  abdomen  of  the  female  are  elongate  like  a  tele- 
scope, forming  a  slender  tapering  ovipositor,  twice  as  long  as  the  re- 
mainder of  the  body  and  as  flexible  as  a  whip-lash.  Standing  on  the 
outside  of  a  green  clover-head,  the  female  inserts  this  organ  among 
the  florets  and  works  it  deeper  and  deeper  until  it  can  go  no  farther. 
The  sensitive  tip  of  the  sinuous  ovipositor  finds  a  suitable  spot  for  an 
egg  and  the  female  becomes  quiet  until  the  egg  is  laid.  The  entire 
process  of  egg-laying  requires  usually  five  minutes,  and  often  ten  to 
fifteen  minutes.  Tho  the  same  female  may  lay  several  eggs  in  one 
clover  head,  she  appears  to  make  it  a  rule  to  distribute  her  eggs  among 
a  good  many  plants.  Many  .females  may,  of  course,  oviposit  in  the 
same  head,  with  the  result  sometimes  that  more  larvae  hatch  than 
can  possibly  find  food.  Thus  in  one  head  of  eighty  florets  the  writer 
found  106  eggs.  Once  in  a  while  an  egg  is  laid  on  a  petal  or  on  the 
calyx  itself,  but  almost  always  it  is  glued  to  one  of  the  hairs  of  the 
immature  calyx,  the  glue  often  forming  quite  a  perceptible  mass.  This 
is  contrary  to  a  published  statement  that  the  eggs  "do  not  appear  to 
be  glued  to  the  hairs." 

The  newly  hatched  larva  has  only  one  way  of  entering  the  ovary 
of  a  flower,  namely,  by  squeezing  in  between  the  unopened  petals,  as 
Comstock  said.  Once  inside  the  flower-bud,  the  maggot,  incapable  of 
biting  any  solid  substance,  sucks  the  fluid  contents  of  the  ovary,  de- 
stroying the  ovule  or  ovules.  An  affected  floret  presents  externally 
a  healthy  appearance  but  the  petals  do  not  expand,  except  rarely. 
They  remain  fresh  and  pink  until  after  the  maggot  leaves  the  bud,  but 
eventually  fade  and  wither  away  without  opening. 

The  simplest  way  to  get  specimens  of  these  larvae  is  to  collect 
clover  heads  that  are  partly  green  and  partly  in  bloom,  and  to  shake 
them  up  a  little,  when  many  of  the  larvae  will  squirm  their  way  out  of 
the  buds.  The  maggots  often  occur  in  great  numbers  on  the  bed  of  a 
hay  wagon  or  the  floor  of  a  barn.  In  a  tight  glass  jar  of  clover  heads 
all  the  larvae  present  will  emerge,  and  the  precise  amount  of  infestation 
can  be  ascertained. 


122  BULLETIN  No.  134  [April 

Tho  the  full-grown  larvae  may  simply  drop  to  the  ground,  as  other 
writers  have  stated,  they  frequently  wriggle  their  way  down  along  the 
stem  of  the  plant,  when  the  latter  is  wet  with  rain.  Indeed,  the  larvae, 
even  when  full  grown,  will  not  emerge  if  the  air  is  too  dry.  Ceci- 
domyiid  larvae  in  general  require  considerable  moisture  for  their  de- 
velopment and  are  very  sensitive  to  the  influence  of  humidity.  Dry- 
ness  causes  the  seed-midge  larvae,  when  on  the  ground,  to  squeeze 
themselves  into  crevices  in  the  soil  and  to  contract  the  body  and  become 
motionless,  as  if  for  pupation.  Even  then,  however,  moisture  will  re- 
peatedly revive  them  to  a  condition  of  wriggling  activity. 

The  period  of  pupation  is  lengthened  by  dryness  and  shortened  by 
moisture.  Prolonged  dryness  kills  both  larvae  and  pupae.  Qut-of-doors 
the  flies  do  not  emerge  during  a  dry  spell ;  continuous  dry  weather 
will  delay  their  appearance  as  much  as  two  weeks ;  but  they  may  be 
expected  to  appear  after  a  rain,  in  the  appropriate  part  of  the  season. 
In  the  insectary,  the  emergence  of  the  flies  can  be  similarly  controlled 
by  moisture,  as  G.  C.  Davis  has  already  noted.  t 

Riley  states  that  the  pupa  works  itself  thru  its  cocoon  and  to  the 
surface  of  the  ground  when  about  to  give  forth  the  fly. 

Autumn  finds  larvae  of  various  sizes  in  the  clover  heads,  in  central 
Illinois.  Most  of  the  larvae  become  full  growTn  and  go  to  the  ground 
in  September ;  the  rest  remain  in  the  heads  and  either  finish  their  growth 
or  else  succumb  to  frost.  In  spite  of  frosts,  full-sized  larvae  may  be 
found  in  the  heads  as  late  as  the  middle  of  October.  October  28,  1907, 
we  found  in  clover  heads  several  larvae  which  were  so  small  (0.8  mm. 
in  length)  that  they  must  have  been  derived  from  late  September  flies, 
and  they  were  altogether  too  small  to  survive  the  imminent  death  of 
their  food  plant. 

The  recognized  injury  done  by  the  seed-midge  to  red  clover  occurs 
during  the  second  year  of  the  plant,  and  the  amount  of  injury  increases 
the  longer  the  plant  is  allowed  to  run. 

Vigorous  plants,  however,  form  heads  during  their  first  year,  and 
in  these  premature  heads  not  a  few  larvae  of  the  seed-midge  are  to  be 
found  in  autumn. 

Natural  Enemies. — The  chalcid,  Bruchophagus  (Eurytoma)  fune- 
bris  How.,  at  first  suspected  of  being  parasitic  upon  the  larva  of  the 
seed-midge,  is  now  known  to  destroy  the  seed  instead  of  the  larva, 
taking  what  the  seed-midge  leaves. 

We  have  reared  from  clover  heads  containing  larvae  of  the  seed- 
midge  two  as  yet  undetermined  species  of  the  chalcid  genus  Tetrasti- 
chus.  These  are  possibly  the  same  two  that  are  mentioned  by  Webster 
as  having  been  reared  directly  from  both  larvae  and  pupae  obtained 
about  Lincoln,  Neb.,  in  December.  In  Delaware,  Sanderson  bred  from 
larvae  of  the  seed-midge,  in  October,  1899,  and  in  June,  1900,  parasites 
determined  by  Ashmead  as  Tetrastichus  carinatus  Forbes  and  Torymus. 

Another  parasite  of  the  seed-midge  is  Anopedias  error  Fitch,  of 
the  family  Platygasteridce,  a  minute  black  species,  about  which  almost 
nothing  has  been  written  since  Comstock,  in  1880,  reported  it  as  emerg- 
ing from  the  cocoon  of  the  clover  seed-midge. 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  123 

An  energetic  enemy  of  the  seed-midge  is  the  common  flower-bug, 
(Triphleps  insidiosus  Say),  as  was  found  some  years  ago  by  Dr. 
Forbes.  I  have  repeatedly  found  a  nymph  or  an  adult  of  this  bug  with 
its  beak  thrust  into  a  seed-midge  larva  or  fly. 

Control. — It  is  by  no  means  necessary  to  abandon  temporarily  the 
raising  of  clover  seed  on  account  of  this  insect,  as  was  once  proposed. 
The  most  effective  and  most  practicable  preventive  is  that  given  by 
Comstock,  namely,  to  cut  the  first  crop  of  clover  as  early  as  possible, 
in  order  to  secure  a  good  seed  crop  at  the  expense  of  a  slight  reduction 
in  the  hay  crop.  The  good  results  of  this  method  are  frequently  ob- 
tained, unconsciously,  by  farmers  who  make  it  a  rule  to  cut  their  clover 
near  the  17th  of  June.  The  writer  was  once  sent  by  our  State  Ento- 
mologist to  examine  injured  clover  on  the  farm  of  A.  E.  Myers,  at 
Millbrook,  111.  (Kendall  Co.).  At  that  place,  August  19,  1903,  there 
were  twenty  acres  of  red  clover  in  full  bloom,  with  the  heads  well  filled 
with  sound  seed,  with  few  green  heads,  and  with  almost  no  sign  of  the 
seed-midge;  no  eggs  were  found  and  only  two  midges  were  seen  dur- 
ing an  extensive  search.  This  clover  had  been  cut  a  few  days  before 
June  25.  Across  the -road  was  another  field  of  red  clover,  similar  in 
history  to  the  first  except  that  it  had  not  been  cut  until  between  July 
4  and  10.  Here  none  of  the  clover  was  in  bloom,  all  the  heads  were 
green,  and  almost  every  head  was  loaded  with  eggs  of  the  seed-midge ; 
often  there  were  more  eggs  in  a  head  than  there  were  florets.  The 
flies  were  abundant  also,  and  were  still  ovipositing.  .In  this  instance, 
a  difference  of  two  weeks  in  the  time  of  cutting  meant  all  the  difference 
between  almost  complete  immunity  and  heavy  infestation. 

Early  cutting  (1)  results  in  the  drying  up  of  the  food  plant  and 
the  undeveloped  larva,  and  (2)  hastens  the  development  of  the  second 
lot  of  clover  heads,  so  that  the  midges  of  the  second  generation  find 
but  few  green  heads  in  which  to  lay  their  eggs. 

The  proper  date  for  early  cutting  depends,  of  course,  on  latitude, 
weather,  and  other  considerations.  It  should  be  not  later  than  June  17 
in  central  Illinois,  and  need  not  be  earlier  than  June  7.  Clover  that  is 
cut  too  green  does  not  cure  well,  but  the  cutting  need  not  be  done  until 
the  field  as  a  whole  is  fresh  with  bloom,  tho  it  should  not  be  delayed 
until  the  flowers  have  withered.  A  clover  head  half  red  and  half 
green  means  that  the  seed-midge  is  present  (or  else  the  seed-cater- 
pillar), and  the  grower  who  will  take  the  trouble  to  study  the  habits  of 
the  midge  will  be  able  to  cut  his  clover  at  just  the  right  time  to  get  rid 
of  the  seed-midge  without  losing  much  of  his  hay  crop. 

Similar  results  may  be  had  by  mowing  back  the  clover  as  early  as 
the  middle  of  May,  in  Illinois  and  Ohio.  This  delays  the  heading 
enough  to  escape  the  second  brood  of  flies. 

Pasturing  in  spring  and  early  summer  exterminates  the  midge  and 
yet  insures  a  good  crop  of  seed,  so  far  as  this  insect  is  concerned.  This 
method,  as  recommended  by  Dr.  Fletcher,  has  been  adopted  with  great 
success  in  Ontario,  Can.  There  the  first  crop  is  pastured  to  cattle  or 
sheep  until  the  beginning  of  June  but  not  later  than  the  middle  of  that 


124  BULLETIN  No.  134  [April, 

month.  In  Michigan,  also,  the  same  method  is  successfully  employed 
by  dairymen,  the  clover  fields  being  pastured  until  the  10th  or  15th  of 
June.  (G.  C.  Davis.) 

Contrary  to  what  might  be  anticipated,  the  seed-midge  neither  flies 
far  nor  is  carried  far  or  in  large  numbers  by  the  wind.  Most  of  the 
midges  that  emerge  in  a  clover  field  stay  there  and  lay  their  eggs  there. 
If  the  wind  blows  they  cling  to  the  clover  plants  or  to  the  ground,  or 
take  but  short  and  occasional  flights.  The  direction  of  flight  is,  to  be 
sure,  determined  by  the  wind  if  the  wind  is  strong,  and  the  midges  are 
certainly  disseminated  more  extensively  by  the  wind  than  by  their  own 
powers  of  flight.  Nevertheless,  the  number  of  midges  carried  from 
one  field  to  another  by  the  wind  is,  in  the  experience  of  the  writer, 
comparatively  small.  For  example,  most  of  the  midges  in  a  given 
field  of  second-year  clover  on  May  25  came  forth  in  that  field  and 
were  the  offspring  of  the  few  midges  that  entered  the  same  field  during 
the  latter  part  of  the  preceding  year.  Hence  it  would  seem  to  be  a 
wise  procedure  to  prevent  the  sporadic  heading  of  first-year  clover  by 
mowing  it  back  a  few  weeks  after  the  oats  (or  other  small  grains) 
have  been  harvested,  at  a  time  when  the  growth  is  vigorous,  but  yet 
sufficiently  early  to  permit  considerable  further  growth  before  frost 
sets  in.  This  cutting  need  not  injure  the  clover.  In  this  state,  red 
clover  is  not  infrequently  cut  in  the  latter  part  of  the  first  season,  for 
a  light  hay  crop,  or  to  prevent  premature  seeding,  and  in  the  good 
growing  season  of  1907,  some  first-year  clover  hay  (mixed  with  stub- 
ble) was  put  on  the  market.  This  cutting  impairs  neither  the  hay 
crop  nor  the  seed  crop  of  the  ensuing  year,  provided  it  is  done  early 
enough  to  allow  the  plants  to  recover  before  winter.  Volunteer  clover 
should  always  be  cut,  as  it  affords  a  rich  nursery  for  all  kinds  of  clover 
insects." 

Where  clover  and  timothy  are  mixed,  early  June  cutting  will, 
in  this  latitude,  sacrifice  the  timothy.  To  obviate  this,  pasture  lightly 
or  clip  back  the  growth  in  May.  This  treatment,  as  Webster  states, 
brings  both  the  first  and  the  second  blooming  of  the  clover  too  late  for 
the  destructive  work  of  the  midge,  and  the  hay  crop  as  a  whole  sus- 
tains no  loss. 

In  a  few  reported  instances,  larvae  of  the  seed-midge  have  been 
found  mixed  with  clover  seed  in  bulk,  and  the  theoretical  danger  of 
sowing  such  larvae  along  with  the  seed  has  been  pointed  out.  While 
we  have  no  direct  evidence  as  -to  the  reality  of  this  danger,  it  would  be 
well,  on  general  principles,  to  kill  such  larvae,  by  drying  them  up  under 
a  gentle  heat,  which  is  said  not  to  injure  the  seed,  or  by  fumigation 
with  bisulfid  of  carbon. 

Dasyneura  leguminicola  Lint. 

1879.  Lintner,  J.  A.— Can.  Ent,  Vol.  XL,  pp.  44,  45,  121-124. 
Riley,  C.  V.— Rep.  Comm.  Agr.,  1878,  pp.  250-252. 

1880.  Comstock,  J.  H.— Rep.  Comm.  Agr.,  1879,  pp.  193-197. 
Lintner,  J.  A. — Thirty-ninth  Rep.  N.  Y.  State  Agr.  Soc., 

1879,  pp.  37-41. 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  125 

Lintner,  J.  A.— Rep.  Ent.  Soc.  Ontario,  1879,  pp.  28-30. 

1881.  Lintner,  J.  A.— Fortieth  Rep.  N.  Y.  State  Agr.  Soc.,  1880, 

pp.  20-24.     Separate,  pp.  11-15. 

1882.  Saunders,  W.— Rep.  Ent.  Soc.  Ontario,  1881,  pp.  38-43. 
1885.     Fletcher,  J. — Rep.  Ent.  Dept.  Agr. •.     Separate,  pp. 

12,  13. 

1891.     Ormerod,  E.  A. — Fourteenth  Rep.  Inj.  Ins.,  pp.  23-27. 
1894.     Davis,  G.  C— Bull.  No.  116,  Mich.  Agr.  Exper.  Sta.,  pp. 

52-56. 
1899.     Hunter,  W.  D.— Ann.  Rep.  Neb.  State  Bd.  Agr.,  1898,  pp. 

247-249. 
1906.     Webster,  F.  M.— Circ.  No.  69,  U.  S.  Dept.  Agr.,  Bur.  Ent., 

pp.  3-7. 

CLOVER  SEED-CHALCID 
Brnchophagus  funebris  How. 

This  abundant  and  energetic  chalcid,  formerly  presumed  to  be  an 
enemy  of  the  clover  seed-midge,  is  now  known  to  be  itself  one  of  the 
worst  of  the  clover  pests.  Instead  of  being  parasitic,  like  most  of  the 
chalcids,  it  eats  out  the  clover  seeds  .and  reduces  the  seed  crop  ma- 
terially. 

The  adults — little,  compact,  black,  flylike  insects — are  common  on 
clover  heads  that  are  fading  and  ripening.  Seeds  containing  the  larvse 
of  this  chalcid  become  brown,  brittle,  and  hollow,  and  when  the  clover 
is  threshed,  the  empty  shells  left  by  the  adults  are  swept  away  with 
the  chaff. 

Not  until  1896  was  this  ubiquitous  insect  suspected  of  being  a 
clover  pest,  and  up  to  the  present  time  its  life  history  and  habits  have 
remained  almost  a  blank,  except  for  what  E.  S.  G.  Titus  has  written. 
The  present  account  makes  considerable  additions  to  the  knowledge 
of  the  subject. 

Distribution. — Vermont,  Rhode  Island,  New  York,  Delaware,  Dis- 
trict of  Columbia,  Virginia,  West  Virginia,  Ohio,  Indiana,  Illinois, 
Michigan,  Kansas,  Mississippi,  Minnesota,  Colorado,  California,  Ore- 
gon, and  Washington.  Most  of  these  records  are  from  Titus,  who 
reared  the  insect  from  clover  heads  obtained  from  various  states. 

Food  Plants. — Red  clover  is  the  chief  food  plant,  tho  crimson 
clover  is  badly  affected,  according  to  Hopkins.  Alfalfa  is  another  food 
plant,  but  one  of  minor  importance  in  my  experience.  I  have  not 
found  the  chalcid  on  white  clover,  but  have  seen  the  adults  on  mam- 
moth clover. 

Injury. — It  was  A.  D.  Hopkins  who  found  that  this  chalcid  eats 
the  seed,  instead  of  being  a  parasite  upon  some  insect. 

The  larva  requires  a  seed  that  is  going  to  grow,  and  this  need  is 
provided  for  by  the  egg-laying  habits  of  the  female.  She  does  not  lay 
her  eggs  in  green  heads,  but  selects,  primarily,  heads  that  have  just 


126 


BULLETIN  No.  134 


[April, 


begun  to  wither,  and,  secondarily,  heads  that  are  in  full  bloom.  Some- 
times I  have  seen  her  trying  in  vain  to  thrust  her  ovipositor  into  a  seed 
that  had  hardened.  The  young  larva  feeds  upon  the  semifluid  albumen 
of  the  cotyledons  of  the  seed;  as  the  seed  hardens,  the  jaws  of  the 
larva  harden  also,  and  at  length  the  larva  has  eaten  out  the  interior  of 
the  seed,  leaving  only  a  thin  shell.  Externally,  an  affected  seed  looks 
unhealthy.  Instead  of  being  blue,  or  clear  yellow  tinged  with  red  or 
purple  at  the  end,  and  plump,  it  is  dull  brown,  often  misshapen  and  a 
little  undersized.  At  threshing  time  some  of  the  adults  have  issued, 
leaving  only  the  shells  of  the  seeds,  and  these  shells  blow  away,  making 
an  unaccountable  shortage  in  the  yield;  other  seeds,  that  still  contain 
the  insect,  may  remain  behind  with  the  sound  seeds,  but  are  of  course 
good  for  nothing.  These  seeds  that  contain  the  insect  are  not  neces- 
sarily so  light  that  they  blow  off  with  the  chaff,  as  one  writer  has 
assumed;  many  of  them,  if  not  most  of  them,  are  heavy  enough  to 
stay  with  the  sound  seeds,  as  I  have  often  found.  The  empty  shells 
are  swept  away.  From  newly  threshed  seed  the  adults  may  continue 
to  emerge  in  swarms,  as  R.  H.  Pettit  noticed.  Thus  the  yield  of  seed 
is  reduced  in  amount,  and  part  of  the  yield  made  valueless,  by  this 
insect. 

August  1  we  examined  49  seeds  taken  at  random,  and  found  35 
to  be  sound  and  14  to  be  infested  by  the  chalcid ;  of  the  latter,  3  were 

empty,  6  contained  each  a 
larva,  4  a  pupa,  and  1  an 
adult.  Titus  has  found 
seed  injured  to  the  extent 
of  40  to  85  percent,  with 
an  average  of  50  percent  to 
the  head. 

Without  examining  the 
seeds  there  is  no  way  of 
telling  whether  the  chalcid 
is  present  or  not,  for  the 
rest  of  the  plant  shows  no 
indication  of  the  presence 
of  the  pest. 

Stages. — The  adult  (Fig. 
1)  is  a  minute,  compact,  flylike  insect,  mostly  black,  but  with  parts  of 
the  legs  yellowish  brown.  It  is  small — the  female  being  1.9  mm.  in 
length  and  the  male  1.7  mm. — yet  its  actions  on  a  clover  head  are  so 
characteristic  that  one  who  has  made  the  acquaintance  of  the  insect 
can  recognize  it  at  once.  Apart  from  its  natural  surroundings,  how- 
ever, one  must  look  to  certain  minute  details  of  structure  in  order  to 
determine  the  species. 

In  the  genus  Bruchophagus  the  marginal  vein  is  linear  and  not 
longer  than  the  stigmal  vein;  the  mesonotum  is  umbilicately  punctate, 
and  the  abdomen  ovate,  pointed,  and  compressed  in  the  female.  The 
male  resembles  the  female  but  lacks  the  point  to  the  abdomen,  and  the 


FIG.  1. — Clover  Seed-chalcid,  Bruchophagus  funebris; 
adult  female.  (Webster,  Circ.  69,  Bur.  Ent,  U.  S. 
Dept.  of  Agriculture.) 


1909] 


THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA 


127 


abdomen  is  shorter  than  in  the  other  sex ;   while  the  male,  unlike  the 
female,  has  oval  funicle  segments  and  long  antennal  hairs. 

The  male  of  this  particular  species,  funebris,  is  black  and  non- 
metallic.  Eyes  dark  brown,  antennae  almost  as  long  as  the  thorax; 
flagellum  of  eight  segments,  there  being  five  in  the  funicle  and  three  in 
the  club;  the  funicle  segments  have  each  a  short  apical  peduncle,  and 
all  but  the  first  of  these  segments  have  either  two  or  three  whorls  of 
yellowish  hairs — usually  three  on  the  second  segment  of  the  funicle 
and  two  on  segments  three  to  five.  The  knees,  anterior  tibiae,  and  all 
the  tarsi  are  light  yellowish  brown.  The  stigma  of  the  wing  gives  off 
a  feeble  branch.  The  abdomen,  joined  to  the  thorax  by  a  short,  stout 
peduncle,  is  small,  being  less  than  half  as  long  as  the  thorax,  and  its 
fourth  segment  is  the  largest. 

The  female  is  like  the  male  in  coloration  but  is  larger,  with  these 
distinctive  characters.     Antennal  segments  not  petiolate,  and  without 
the  long  hairs;  flagellum  of  nine  segments,  the  funicle  having  six  and 
the    club   three.     Abdomen    not   pedunculate, 
longer  than  the  thorax,  with  the  fourth  and 
fifth  segments  short  and  subequal,  and  with  a 
light  brown  pointed  extremity — a  part  of  the 
ovipositor. 


FIG.  3. 


FIG.  4. 


FIG.  2. — Clover  Seed-chalcid, 
Bruchophagus  funebris, 
eggs.  Greatly  enlarged. 


Clover  Seed-chalcid,  Bruchophagus  funebris:  Fig.  3,  larva, 
and  head  at  right;  Fig.  4,  pupa.  (Webster,  Circ.  69,  Bur. 
Ent.,  U.  S.  Dept.  of  Agriculture.) 


The  egg  (Fig.  2)  is  broadly  elliptical  to  ovate  in  form,  ending 
anteriorly  in  a  small  papilla  and  prolonged  posteriorly  as  a  slender 
tube,  at  least  twice  as  long  as  the  egg  proper,  which  averages  0.26  mm. 
in  length.  The  egg  when  laid  is  translucent  whitish,  and  smooth ; 
within  a  day,  the  appendage  shrinks  and  turns  brown. 

The  maggotlike  larva  (Fig.  3)  is  white,  stout,  and  footless,  with  a 
small  head;  length,  when  full  grown,  1.5  to  2  mm.  The  larva  shows 
few  distinctive  characters,  tho  it  is  stouter  and  less  active  than  para- 
sitic larvae  of  the  same  family. 

The  pupa  (Fig.  4)  is  for  a  time  white,  but  darkens  as  the  color 
of  the  imago  develops;  length  1.9  mm. 

Life  History. — In  1904  and  1905  we  made  daily  observations  on 
the  number  of  adults  emerging  from  clover  heads  collected  thruout  the 
season  and  kept  in  large  glass  jars — each  lot  having  been  collected  at 
one  time  and  place.  The  observations  when  plotted  on  coordinate 
paper  showed  several  new  things. 


128  BULLETIN  No.  134  [April, 

Beginning  April  14,  there  was  a  gradual  increase  in  the  number 
of  emergences  up  to  June  6  and  12;  then  a  rapid  decrease  to  July  6; 
afterward  a  sudden  rise  from  August  4  to  a  high  maximum  August  10, 
followed  by  a  rapid  drop  to  August  24,  after  which  date  adults  issued 
constantly,  but  in  moderate  numbers,  until  October  15.  Out-of-doors 
the  adults  do  not  begin  to  emerge  until  about  May  15,  as  a  rule,  and  in 
1907  no  adults  were  seen  until  May  23,  tho  the  clover  fields  had  been 
searched  almost  every  day  for  them.  The  June  and  August  dates  of 
maximum  emergence  in  the  insectary  agreed  with  the  dates  of  maxi- 
mum abundance  in  the  field.  One  year,  however,  I  found  the  chalcids 
common  July  6  to  19,  and  very  common  about  July  15,  tho  in  most 
years  there  are  but  two  times  of  greatest  abundance,  and  these  are  when 
faded  clover  blossoms  are  most  numerous  in  the  fields  of  cultivated 
clover.  Some  adults  can  be  found,  however,  almost  any  day  in  the 
season  from  May  15  to  October  15,  or  later,  especially  on  volunteer 
clover,  where  they  can  always  find  heads  in  just  the  right  condition  for 
oviposition. 

The  insect  passes  the  winter  inside  the  seed,  on  the  ground.  The 
seeds  that  we  have  collected  and  examined  in  early  March  contained 
larvae  only ;  in  late  autumn  the  seeds  taken  from  dead  clover  heads  on 
the  ground  contained  many  larvae  and  now  and  then  a  pupa.  Evidently 
the  species  winters  chiefly,  if  not  almost  entirely,  as.  a  larva,  in  this 
region. 

As  the  first  period  of  egg-laying  extends  over  a  month  or  more, 
there  is  a  corresponding  range  in  the  time  of  emergence  of  the  second 
lot  of  adults.  Thus,  clover  heads  collected  June  18  gave  adults  June 
21  and  every  day  from  July  4  to  July  20. 

More  than  this,  there  occurs  a  surprising  extension  of  the  period 
of  emergence.  For  example,  heads  collected  June  21,  1904  (Urbana, 
111.),  gave  adults  June  24;  July  2,  4,  5,  6;  August  9,  10,  11,  12,  13; 
then  no  more  until  the  next  year,  1905,  when  more  adults  issued  May 
27,  30,  and  June  5.  Thus  the  last  adults  appeared  almost  a  year  later 
than  the  first  ones — all  these  from  eggs  laid  inside  a  period  of  one 
month.  One  to  nine  individuals  issued  on  each  of  these  dates,  and  the 
majority  issued  during  the  first  year. 

Compare  this  record  with  the  above:  Heads  collected  June  28, 
1904  (De  Kalb  Co.,  111.)  gave  adults  (in  Urbana)  July  2  (5  individu- 
als) ;  August  8  (1),  12  (4),  15  (1),  19  (1),  and  no  more  until  19G5 ; 
then  adults  issued  May  30  (2),  31  (2)  ;  June  1  (11),  2  (2),  3  (2),  5 
(11),  6  (24), 7  (8),  8  (3),  9  (9),  10  (4),  12  (35),  13  (10),  14  (12), 
15  (18),  16  (8),  17  (8),  19  (7),  20  (2),  22  (2),  24  (2),  and  none 
thereafter.  Here,  the  great  majority  failed  to  emerge  until  the  follow- 
ing year.  Usually  it  is  the  other  way. 

By  July  15  or  a  little  earlier,  new  eggs  begin  to  be  laid  in  the  new 
growth  of  red  clover — the  seed  crop.  We  collected  an  immense  num- 
ber of  clover  heads  July  28,  1904,  which  gave  adults  as  follows :  Au- 
gust 5  (many),  7  and  8  (194  individuals),  9  (42),  10  and  11  (13),  12 
(103),  13  (23),  14  (6),  15  (31),  16  (6),  17  (2),  18  (1),  19  (3),  22 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  129 

(8)  ;  then  no  more  until  1905,  when  a  few  issued  May  24  (2),  29  (3), 
June  5(1),  7(1);  then  no  more — observations  ceasing  August  8.  In 
this  case,  the  majority  emerged  near  the  middle  of  August  and  the 
minority  waited  until  the  next  year. 

Taking  heads  collected  still  later  in  the  season — August  26,  1904 — 
these  gave  imagines  August  30  (a  few),  31  (a  few),  September  1 
(few),  2  (few),  4,  5,  6,  7,  8,  9,  11,  12,  14,  15,  16,  17,  18,  19,  20,  21,  23, 
25,  26,  29,  October  6  (one  individual  on  each  of  these  last  dates,  with 
two  exceptions)  ;  then,  in  1905,  May  12  (5),  16  (many),  19  (many), 
20  (8),  23  (1),  26  (1),  June  2(1),  and  no  more  up  to  September  1, 
when  the  daily  observations  were  discontinued. 

Heads  collected  September  7  gave  a  few  adults  in  September  and 
October,  but  very  many  more  in  the  following  April  and  May. 

Heads  collected  September  16,  October  3,  17,  and  27,  gave  no 
adults  until  the  following  April,  May,  and  June,  when  large  numbers 
issued. 

In  the  last  three  instances  most  or  all-  of  the  adults  did  not  issue 
until  the  next  year.  Thus  the  time  of  emergence  is  delayed  in  propor- 
tion to  the  lateness  of  oviposition. 

These  records  are  by  no  means  exceptional ;  they  are  typical ;  those 
given  here  were  selected  from  some  twenty  as  being  the  most  complete 
and  most  significant  for  present  purposes. 

To  summarize:  The  May  and  June  adults  lay  their  eggs  in  the 
first  growth  of  second-year  red  clover,  and  most  of  the  adults  derived 
from  these  eggs  appear  in  July  and  August,  but  some  of  them  do  not 
issue  until  the  following  May  or  June.  The  July  and  August  adults 
lay  their  eggs  in  the  second  growth,  and  some  of  the  adults  from  these 
appear  during  the  same  season ;  the  rest  not  until  the  following  year. 
The  later  the  eggs  are  laid  the  larger  the  proportion  of  individuals  to 
lie  over  until  the  next  year.  The  adults  have  two  times  of  greatest 
abundance,  falling  near  June  12  and  August  12  .respectively.  This 
does  not  mean  only  two  generations,  however,  but,  instead,  two  lots  of 
individuals.  The  first  lot  (June  12)  is  derived  from  eggs  laid  thruout 
the  previous  season.  The  second  lot  (August  12)  has  no  accessions 
from  the  previous  year,  but  is,  nevertheless,  composite  in  its  nature, 
for  it  consists  of  adults  of  both  the  second  generation  and  the  third. 
I  have  traced  as  many  as  three  generations  per  year,  and  there  is 
clearly  a  possibility  of  four.  The  fact  that  some  members  of  each  gen- 
eration lie  over  until  the  next  year  complicates  the  study  of  the  life 
history. 

At  first,  it  seemed  to  me  at  least  possible  that  the  prolongation  of 
the  period  of  emergence  might  really  be  due  to  re-oviposition  in  the  old 
clover  heads,  even  tho  the  chalcids  had  been  removed  every  day  as  fast 
as  they  came  to  light  and  no  copulation  had  been  observed.  This  as- 
sumption was  dismissed,  however,  after  being  tested,  for  the  seeds 
were  all  too  dry  and  hard  to  be  penetrated  by  the  ovipositor  or  to  serve 
as  larval  food.  There  remained  only  the  possibility  that  some  chal- 
cids had  emerged  soon  enough  after  the  clover  heads  were  collected  to 


130  BULLETIN  No.  134  [April. 

find  seeds  soft  enough  for  oviposition,  but  this  possibility  was  too  slight 
to  account  for  the  immense  number  of  late-emerging  chalcids.  Fur- 
thermore, any  larvae  from  eggs  laid  in  the  jars  of  clover  heads  would 
soon  be  disposed  of-  by  the  drying  and  shriveling  of  the  green  seeds.  I 
could  not  find  any  evidence  of  re-oviposition. 

There  is  one  source  of  possible  confusion  that  must  be  guarded 
against  in  studying  the  life  history  of  this  chalcid.  There  emerges 
from  the  clover  heads,  along  with  B.  funebris,  another  chalcid,  Tetras- 
tichus  bruchophagi  Ashm.  MS.,  so  named  upon  the  assumption  that  it 
is  a  parasite  of  the  clover  seed-chalcid.  This  Tetrastichus  is  so  much 
like  the  Bruchophagus  in  general  appearance  that  it  might  hastily  be 
mistaken  for  the  latter,  tho  many  differences  between  the  two  appear 
under  the  microscope. 

Habits. — While  the  clover  heads  are  green,  in  spring,  few  if  any 
of  the  seed-chalcids  will  be  found ;  but  when  they  begin  to  turn  brown, 
the  chalcids  appear  on  them.  The  males  appear  four  or  five  days 
earlier  than  the  females,  and  both  sexes  frequent  the  clover  heads,  but 
the  males  do  not  rush  about  and  explore  the  recesses  of  the  clover  head 
in  the  way  that  the  females  do. 

On  warm  sunny  days  the  chalcids  are  most  active,  and  then  most 
of  the  eggs  are  laid.  On  rainy  days  both  sexes  remain  quietly  in  the 
clover  heads.  They  make  their  home  among  the  florets,  and  there,  at 
length,  their  dead  bodies  are  to  be  found. 

Brown  ripe  clover  heads  give  the  female  much  trouble,  for  she 
can  not  insert  her  ovipositor  into  a  hard  seed ;  green  heads  she  passes 
by;  florets  in  full  bloom  receive  some  attention  and  some  eggs;  but 
most  of  the  eggs  are  laid  in  florets  with  withering  corollas. 

The  males  are  quick  to  fly  when  one  brings  a  hand  lens  near  them, 
but  the  busy  females  occasion  the  observer  less  difficulty.  The  female 
squeezes  in  and  out  among  the  florets,  often  working  her  way  deep  into 
the  flower  head,  so  that  one  must  cautiously  spread  the  florets  apart 
in  order  to  follow  her  movements.  Every  now  and  then  she  stops  to 
clean  her  antennae  with  the  front  legs,  or  her  wings  and  abdomen  by 
passing  the  hind  legs  backward.  With  the  tips  of  her  palpitating  an- 
tennae she  keeps  touching  the  florets,  especially  the  calyx,  as  if  testing 
it.  At  length  she  proceeds  to  lay  an  egg,  and  usually  pierces  the  side 
of  the  calyx  tube,  tho  sometimes  she  stands  on  the  top  of  the  calyx, 
between  the  calyx  lobes  and  the  corolla.  Bending  the  end  of  the  abdo- 
men forward  under  the  body,  she  releases  the  long  needlelike  ovipos- 
itor and  thrusts  it  into  the  calyx ;  then  the  abdomen  recovers  its  normal 
form,  but  the  ovipositor,  at  right  angles  to  the  body,  remains  inserted 
in  the  wall  of  the  calyx,  and  is  pushed  and  wriggled  until  its  tip  has 
entered  the  young  seed.  After  three  to  twelve  minutes  the  organ  is 
withdrawn  and  rapidly  slipped  back  into  place.  Sometimes  a  tiny  col- 
orless drop  of  fluid  is  seen  at  the  tip  of  the  ovipositor  just  before  it 
is  thrust  into  the  calyx. 

The  observer,  having  identified  the  floret  during  the  process  of 
oviposition,  can  then  pry  it  out  with  a  knife  and  carry  it  back  to  be 


1909]  THE  INSECT  PKSTS  OF  CLOVER  AND  ALFALFA  131 

dissected  under  a  microscope,  if  he  wishes  to  find  the  egg.  The  egg  is 
found  inside  the  seed  in  the  semifluid  albumen.  Being  translucent  and 
almost  colorless,  the  freshly  laid  egg  transmits  the  pale  green  color  of 
the  surrounding  seed  tissue  and  is  inconspicuous ;  but  as  one  dissects 
the  albumen  carefully,  the  egg  comes  out  like  a  lump  of  jelly,  soft  and 
delicate  but  sufficiently  elastic  to  keep  its  form.  The  egg  varies  con- 
siderably in  shape  and  must  assume  its  definite  form  after  leaving  the 
ovipositor;  for  the  body  of  the  egg  is  wider  than  the  channel  of  the 
ovipositor,  and  no  distension  of  the  organ  is  seen  during  oviposition. 
It  is  to  be  inferred  that  the  egg  passes  thru  the  ovipositor  in  the  form 
of  a  long  thread,  the  body  part  of  the  egg  entering  the  seed  first  and  at 
once  expanding.  The  usual  position  of  the  egg  in  the  seed,  with  the 
end  of  the  appendage  near  the  seed  coats  and  the  body  of  the  egg 
farther  away,  indicates  that  the  body  entered  first.  The  appendage 
probably  serves  as  a  reservoir  for  some  of  the  egg-contents  while  the 
egg  is  going  thru  the  ovipositor.  This  appendage  is  empty  in  the 
freshly  laid  egg,  and  within  a  day  after  the  latter  is  laid  the  former 
shrinks  and  turns  brown — then  affording  a  ready  means  of  locating  the 
egg.  Without  a  careful  dissection  this  delicate  appendage  will  be 
missed. 

The  seeds  in  which  the  eggs  are  laid  look  sound  and  healthy  and 
contain  no  other  insect — so  we  have  always  found. 

The  egg,  dissected  out  of  a  seed,  can  be  kept  for  some  time  in  a 
glass  tube,  upon  a  piece  of  moist  black  paper  or  a  fragment  of  albumen 
taken  from  the  seed,  and  can  be  examined  daily  under  the  microscope 
in  order  to  determine  the  egg  period.  We  kept  eggs  in  this  way  for 
thirteen  days,  after  which  they  appeared  to  be  dead.  Another  way  is 
to  take  a  large  number  of  seeds  from  florets  in  which  the  females  were 
seen  to  oviposit,  and  to  dissect  these  at  successively  longer  intervals 
from  the  time  of  oviposition,  making  sure  that  there  is  not  more  than 
one  egg  in  each  seed.  By  this  method  I  found  that  eggs  laid  July  22 
were  unhatched  and  apparently  sound  thirteen  days  afterward,  but  then 
the  material  gave  out,  and  I  do  not  yet  know  precisely  the  duration  of 
the  egg  stage. 

The  larva  when  full  grown  fills  the  seed,  leaving  only  the  shell 
intact. 

The  adult  emerges  thru  an  irregular  hole,  generally  at  the  top  of 
the  seed  (as  the  seed  stands  in  the  calyx).  In  one  instance  I  saw  such 
a  hole  in  the  seed  when  the  seed  contained  not  an  adult,  but  a  pupa. 
The  opening  was  no  doubt  made  by  the  larva  but  was  probably  acci- 
dental— for  among  phytophagous  chalcids  in  general  the  exit  opening 
is  bitten  out  by  the  adult,  not  by  the  larva. 

Natural  Enemies. — In  company  with  the  seed-chalcid,  there 
emerged  frequently,  in  our  jars  of  clover  heads,  a  second  black  chalcid 
which  might  casually  be  mistaken  for  the  first  species,  tho  belonging  to 
another  genus — Tetrastichus.  The  species  is  T.  bruchophagi  Ashm. 
MS.,  as  determined  from  specimens  named  by  Ashmead  himself,  and 
obtained  by  Mr.  R.  L.  Webster  from  Prof.  Lawrence  Bruner.  The 


132  BULLETIN  No.  134  [April, 

specific  name  may  or  may  not  prove  to  be  appropriate  in  its  meaning. 
At  present  I  know  of  no  direct  evidence  that  the  Tetraslichus  feeds  on 
the  seed-chalcid,  but  the  parasitic  habit  of  other  members  of  the 
genus,  and  the  association  of  this  species  with  the  seed-chalcid,  in  the 
apparent  absence  of  other  possible  hosts,  leads  one  tentatively  to  regard 
the  Tetrastichus  as  an  enemy  of  the  destructive  clover  seed-chalcid. 

Control. — All  things  considered,  the  shortage  of  the  seed  crop,  as 
a  constant  occurrence,  is  due  chiefly  to  the  seed-midge  and  the  seed- 
chalcid,  in  this  state.  Probably  the  midge  is  a  little  more  injurious 
than  the  chalcid;  at  least,  the  larvae  of  the  former  are  a  little  more 
abundant  than  those  of  the  latter. 

The  chalcid  has  not  attracted  the  attention  that  it  will  from  eco- 
nomic entomologists,  and  nothing  in  the  way  of  preventive  measures  has 
been  proposed  except  the  cautious  statement  by  Webster  that  the  same 
means  recommended  for  the  midge  might  apply  to  the  chalcid,  and  that 
the  destruction  of  outstanding  clover  heads  and  the  burning  of  chaff 
and  stems  after  hulling  would  in  all  probability  greatly  reduce  the 
numbers  of  the  insect. 

It  is  safe  to  say  that  early  cutting  in  June  would  undoubtedly  pre- 
vent a  great  amount  of  oviposition,  S.nd  if  done  as  soon  as  the  field 
came  into  bloom,  would  not  only  forestall  most  of  the  oviposition,  but 
would  also  dispose  of  any  eggs  or  young  larvae  that  might  already  be 
present  in  the  tender  green  seeds ;  for  the  green  unhardened  seeds  dry 
out  and  shrivel  up  soon  after  the  leaves  and  stems  dry.  Moreover, 
early  cutting  of  the  hay  crop  would  hasten  the  maturity  of  the  seed 
crop  in  a  way  to  prevent  most  of  the  midsummer  oviposition ;  not  all  of 
it,  of  course,  for  some  chalcids  would  be  on  the  wing  whenever  the 
clover  heads  ripened.  It  is  true,  however,  that  the  life  history  of  the 
chalcid  has  become  adapted  to  that  of  red  clover  as  it  is  usually  cul- 
tivated, and  that  the  two  periods  of  maximum  abundance  of  the  chal- 
cid coincide  with  those  of  the  greatest  abundance  of  ripening  clover 
heads;  and  it  follows  that  the  methods  given  would  largely  derange 
this  adjustment. 

The  fact  that  the  insect  passes  the  winter  inside  the  seeds  on  the 
ground  indicates  plowing  under  as  a  preventive.  This  is  ordinarily 
done  anyway  after  the  second  year  of  the  clover,  and  when  done  at  the 
usual  time — as  early  as  practicable  in  spring — the  plowing  doubtless 
buries  most  of  the  insects  beyond  the  possibility  of  emergence. 

In  first-year  clover  the  chalcid  lays  eggs  in  such  heads  as  may  be 
present  in  -the  latter  part  of  the  season,  and  these  heads  are  often 
numerous.  Their  seeds,  falling  to  the  ground,  furnish  no  small  pro- 
portion of  the  chalcids  that  appear  in  the  same  field  the  following  May 
and  June.  It  would  seem  wise,  therefore,  to  clip  off  or  pasture  off  the 
heads  of  first-year  red  clover.  In  fact,  something  of  a  fodder  crop 
can  be  obtained  in  the  latter  part  of  the  first  season  without  injury  to 
the  plant,  if  the  cutting  is  not  done  too  late  in  the  season. 

Volunteer  clover  is  always  infested  by  the  chalcid,  as  well  as  by 
other  pests,  and  ought  to  be  destroyed. 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  133 

I  have  several  times  examined  commercial  clover  seed  and  found 
some  of  it  injured  by  this  insect,  but  the  inmates  of  the  seeds  always 
happened  to  be  dead.  There  is  a  strong  possibility,  however,  that  new 
clover  seed  takes  the  living  insect  to  the  field.  Such  seed,  if  sown 
broadcast,  would  permit  the  adults  to  emerge ;  but  if  drilled  in,  would 
dispose  of  the  chalcids,  as  they  could  scarcely  make  their  way  to  the 
surface. 

Bruchophagus  funebris  How. 

1880.     Howard,  L.  O.— Rep.  [U.  S.]  Comm.  Agr.,  1879,  p.  196. 
1896.     Hopkins,  A.  D.— Bull.  No.  6,  U.  S.  Dept.  Agr.,  Div.  Ent., 
p.  73. 

1898.  Hopkins,  A.  D.— Bull.  No.  17,- U.  S.  Dept.  Agr.,  Div.  Ent., 

p.  '45. 

1899.  Pettit,  R.  H.— Bull.  No.  175,  Mich.  Agr.  Exper.  Sta.,  pp. 

366,  367. 
1904.     Titus,  E.  S.  G.— Bull.  No.  44,  U.  S.  Dept.  Agr.,  Div.  Ent., 

pp.  77-80. 
1906.     Webster,  F.  M.— Circ.  No.  69,  U.  S.  Dept.  Agr.,  Bur.  Ent., 

pp.  7-9. 


CLOVER  SEED-CATERPILLAR 

Enarmonia  inter stinctana  Clem. 

(Grapholitha  interstinctana) 

In  its  ability  to  diminish  the  seed  crop,  this  pest  ranks  with  the 
seed-midge  and  the  seed-chalcid.  Attacking  a  clover  head  that  is 
green  or  partly  in  bloom,  the  little  caterpillar  eats  out  a  cavity  in  the 
head,  destroying  many  of  the  unopened  buds  and  some  of  the  tender 
green  seeds,  and  spoiling  the  head  as  a  whole.  When  no  young  clover 
heads  are  at  hand,  the  caterpillar  feeds  on  tender  green  leaves  at  the 
crown  of  the  plant. 

The  adult  is  an  inconspicuous  little  brown  moth  of  the  family 
Tortricida,  and  may  be  recognized  by  means  of  its  peculiar  silvery 
markings. 

Distribution. — The  published  records  show  that  this  insect  is  pres- 
ent in  Maine,  Massachusetts,  New  York,  Pennsylvania,  Washington 
(D.  C),  Ohio,  Indiana,  Illinois,  Iowa,  Missouri,  and  Michigan.  It 
probably  occurs  in  other  states.  In  Illinois  it  is  well  established  thru- 
out  the  state,  holding  its  own  every  year,  and  becoming  locally  abun- 
dant now  and  then. 

Food  Plants  and  Injuries. — The  chief  food  plant  is  red  clover,  but 
white  clover  is  also  affected,  and  we  have  reared  the  species  from 
alsike.  Lintner  quoted  a  correspondent  to  the  effect  that  mammoth 
clover  was  not  touched  by  a  certain  insect  which  Lintner  (Eleventh 
Report,  p.  153)  took  to  be  the  seed-caterpillar.  The  correspondent's  let- 
ter evidently  refers,  however,  not  to  this  insect  at  all,  but  to  the  seed- 
chalcid.  There  appears  to  be  no  reason  why  mammoth  clover  should 


134  BULLKTIN  No.  134  [April, 

be  exempt  from  the  seed-caterpillar,  and  we  have  actually  found  it  on 
so-called  mammoth,  which  appeared  to  be  a  cross  between  mammoth 
and  the  common  red  clover. 

•Hatching  usually  near  the  base  'of  a  green  clover-head,  the  larvn 
eats  into  the  head,  destroying  the  green  florets  as  it  goes.  A  small 
green  head  is  often  destroyed  entirely,  before  it  is  many  days  old;  a 
larger  head  is  injured  only  locally  at  first,  remaining  green  on  one 
side,  while  the  other  and  unaffected  side  may  come  into  full  bloom 
(PL  L,  Fig.  9).  To  judge  from  the  external  appearance  of  the  head, 
either  the  seed-caterpillar  or  the  seed-midge  larva  might  be  the  author 
of  the  mischief,  and  both  are  often  present  at  the  same  time.  A  midge 
larva,  however,  is  hidden  away  in  the  ovary  of  a  single  floret,  while  the 
seed-caterpillar  makes  a  large  dirty  excavation  involving  many  florets, 
and  is  readily  brought  to  light  by  tearing  open  the  clover  head.  The 
caterpillar  attacks  particularly  the  bases  of  the  florets,  and  eats  every- 
thing, including  *the  semifluid  ovules ;  occasionally  it  eats  a  soft  green 
seed  but  it  does  not  eat  into  seeds  that  have  hardened.  Not  infre- 
quently two  larvae  are  found  in  the  same  head.  Even  when  the  direct 
injury  is  confined  to  a  portion  of  a  clover  head,  the  entire  head  is 
ruined,  for  it  at  length  dries  up  and  loses  the  rest  of  its  florets,  leaving 
only  the  dead  brown  receptacle. 

Less  conspicuous,  tho  not  inconsiderable,  is  the  injury  at  the 
crown  of  the  plant,  done  chiefly  in  September  and  October,  by  cater- 
pillars of  the  same  species  feeding  on  the  young  leaves. 

The  total  amount  of  injury  by  this  insect  is,  of  course,  variable. 
In  New  York,  Comstock  once  found  15  to  20  percent  of  the  heads  of 
red  clover  infested.  In  Michigan,  Webster  saw  clover  injured  to  the 
extent  of  95  percent.  In  Iowa,  Gillette,  Osborn,  and  Gossard  have 
found  the  severest  kind  of  infestation.  While  not  sufficiently  abun- 
dant to  attract  attention,  the  insect  is,  nevertheless,  the  unsuspected 
cause  of  a  considerable  reduction  in  the  seed  crop;  for  the  destruction 
of  one  head  by  a  caterpillar  means  a  loss  of  more  than  one  hundred 
seeds. 

Stages. — The  egg,  hitherto  undescribed,  is  at  first  green,  then  yel- 
lowish, white,  and  is  almost  orbicular  as  seen  from  above,  tho  it  is 
flattened  ventrally ;  the  surface  is  finely  granulate  and  iridescent.  The 
dimensions  are  as  follows :  length,  0.275  mm. ;  width,  0.26  mm. ;  and 
height,  0.21  mm. 

The  full-grown  caterpillar,  7  or  8  mm.  long,  has  the  usual  five 
pairs  of  prolegs.  The  color  varies  in  accordance  with  the  nature  of 
the  food  (green  tissue,  or  red  floral  tissue)  from  dirty  white,  tinged 
with  green,  to  orange,  as  in  Figure  10  of  Plate  I.  The  alimentary  canal 
with  its  greenish  or  purplish  contents  shows  thru  the  translucent  skin 
and  shifts  in  position  as  the  caterpillar  moves.  The  head  is  dark 
brown  and  polished,  caudate  occipitally,  and  deeply  immersed  in  the 
prothorax.  Prothoracic  shield  yellowish  with  a  brown  posterior  bor- 
der interrupted  by  a  median  line  of  white ;  or  else  dark  brown  with  a 
clear  median  line.  The  body  bears  not  a  few  pale  stiff  hairs,  and  the 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  135 

dorsal  piliferous  tubercles  are  arranged,  as  Comstock  noted,  in  two 
pairs,  those  of  the  anterior  pair  being  closer  together  than  those  of  the 
posterior  pair. 

Comstock  has  already  described  the  pupa  in  detail.  Essentially, 
it  is  5  mm.  long,  brown,  with  the  wing-cases  and  the  dorsum  of  the 
thorax  darker  than  the  rest.  There  are  two  transverse  rows  of  teeth 
on  the  dorsum  of  all  the  evident  abdominal  segments  except  the  last, 
and  the  blunt  anal  segment  bears  posteriorly  six  stout  blackish  ex- 
curved  hooks,  and  several  delicate  hooked  filaments. 

The  oval  white  silken  cocoon,  10  mm.  long,  is  usually  inconspicu- 
ous on  account  of  the  particles  of  excrement  or  bits  of  floral  tissue 
attached  to  it. 

The  adult  (Plate  I.,  Fig.  11),  expanding  only  8  to  10  mm.,  is  a  silky 
dark  brown  moth,  with  brilliant  silvery  markings  that  are  quite  char- 
acteristic. The  most  conspicuous  marks  are  those  that  make  the  two 
parallel  crescents  when  the  wings  are  closed.  Along  the  anterior  bor- 
der of  the  front  wing  are  eight  silvery  marks  (sometimes  nine)  in 
form  and  position  as  shown  in  the  figure.  In  fresh  specimens  the 
front  wings  show  a  few  patches  of  iridescent  scales.  The  hind  wings 
are  dark  brown,  with  pale  fringes. 

Life  History. — Our  field  and  insectary  observations  show  that 
there  are  three  generations  of  this  species  every  year,  without  much 
overlapping  of  the  broods.  Here,  the  moths  of  the  first  generation  be- 
gin to  emerge  from  the  pupae  May  15,  attain  their  maximum  numbers 
May  24  (along  with  the  clover  seed-midge),  and  disappear  during  the 
last  of  June.  In  1907 — a  late  season — we  saw  no  moths  until  May  21, 
and  they  were  most  numerous  May  30.  The  moths  of  the  second  gen- 
eration appear  in  the  form  of  a  few  scattering  individuals  as  early  as 
June  25,  but  most  of  them  are  on  the  wing  during  the  third  week  of 
July,  and  a  few  battered  specimens  linger  over  into  the  first  week  of 
August.  The  moths  of  the  third  generation  appear  as  early  as  Au- 
gust 19,  become  abundant  by  August  30,  continue  to  emerge  as  late  as 
September  12,  and  die  off  by  the  last  of  September.  Some  margin — 
a  few  days — should,  of  course,  be  allowed  for  these  dates,  which  are 
here  given  as  they  appear  on  our  note-slips. 

Eggs  laid  September  2  hatched  September  7.  The  larval  period 
is  from  one  month  to  five  weeks.  The  pupal  period  in  July  is  between 
two  and  three  weeks.  It  is  possible  to  find  larvae  of  various  sizes  at 
any  time  from  the  last  week  of  May  until  winter  sets  in,  tho  larvae  are 
few  and  far  between  when  the  moths  are  most  numerous. 

The  moths  of  the  third  brood  lay  their  eggs  at  once,  and  these 
hatch  in  five  or  six  days;  but  the  further  life  history  becomes  twofold, 
depending  on  where  the  eggs  are  laid.  In  the  insectary  the  moths  lay 
their  eggs  preferably  on  young  clover  heads,  but  if  not  supplied  with 
these  they  oviposit  erratically  on  fresh  or  dead  leaves  or  stems.  Out- 
of-doors  in  September  and  October  the  larvae  occur  in  two  situations ; 
either  in  immature  clover  heads,  or  at  the  crown  of  the  plant.  In  the 
clover  heads  active  larvae  can  be  found  thruout  October,  in  spite  of  the 


136  BULLETIN  No.  134  [April, 

frost,  and  a  large  proportion  of  these  doubtless  succeed  in  pupating 
before  winter  overtakes  them.  In  the  insectary,  pupation  in  October 
is  the  rule.  Larvae  which  hatched  September  7  spun  cocoons  October 
14,  and  pupated  October  16.  One  larva  pupated  September  2,  and  the 
moth  emerged  June  27. 

The  fate  of  the  larvae  that  feed  at  the  crown  of  the  plant  in  au- 
tumn is  rather  uncertain.  The  earliest  ones  probably  pupate,  and  some 
of  the  remainder  very  likely  survive  the  winter  as  larvae.  We  have  not 
been  able  as  yet  to  find  any  of  the  larvae  in  early  spring,  but  in  Iowa, 
following  a  year  of  heavy  infestation,  Gossard  found  full  grown  larvae 
under  rubbish  and  manure,  and  partly  grown  larvae  still  in  the  crowns 
of  the  plants,  April  22,  tho  the  number  found  was  only  25  percent  of 
that  found  the  preceding  autumn. 

Habits. — The  moths  appear  in  spring  along  with  the  first  green 
heads  of  the  red  clover.  When  disturbed  they  take  short  rapid  zigzag 
flights  and  come  to  rest  on  a  clover  plant.  In  the  hot  sunlight  they 
seek  the  shaded  side  of  a  stem  or  the  under  side  of  a  leaf,  but  in  the 
cooler  and  darker  parts  of  the  day  and  in  cloudy  weather  they  often 
alight  in  full  view,  and  close  the  wings,  forming  a  little  brown  triangle 
marked  with  a  silvery  double  crescent  as  in  Figure  11,  Plate  I. 

The  moth,  upon  alighting,  has  the  peculiar  habit,  already  remarked 
by  others,  of  whirling  about  in  a  circle  several  times,  with  the  head  as 
a  pivot,  and  then  reversing  the  movement  before  settling  to  rest.  No 
explanation  for  this  performance  is  evident. 

Osborn  and  Gossard  have  reported  the  moths  as  being  especially 
active  in  early  evening,  when  they  hovered  over  the  clover  blossoms 
in  such  numbers  as  to  form  a  perfect  cloud  between  the  observer  and 
the  sun. 

In  clover  that  is  forming  heads,  nearly  all  the  larvae  are  at  work 
in  the  heads,  but  a  few  are  present  in  unexpanded  leaf-buds,  eating  out 
the  interior  tissue. 

In  first-year  clover  that  has  not  headed,  and  in  second-year  clover 
that  has  been  recently  cut,  the  eggs  are  laid,  singly  a's  usual,  on  young 
stems  and  leaflets  at  or  near  the  base  of  the.  plant,  where  the  larvae 
hatch  and  remain. 

In  first-year  clover  with  oats,  the  moths  are  abundant  in  the  new 
growth  after  harvest.  Such  was  the  case  in  a  field  in  Urbana  August 
30,  1907,  at  which  time  none  of  the  new  growth  had  headed.  In  an 
adjoining  field  of  second-year  clover,  the  heads  of  which  were  nearly 
all  brown,  the  moths  had  disappeared,  leaving  the  seed-chalcid  in 
charge  of  the  crop.  In  September,  a  good  many  green  heads  occur  on 
first-year  clover,  and  in  these  the  moths  lay  eggs  rather  abundantly. 
Volunteer  clover  is  always  infested  by  the  seed-caterpillar. 

The  cocoon  is  spun  in  a  clover  head  or  at  the  surface  of  the 
ground,  according  to  the  situation  of  the  larva.  Comstock  gives  twenty 
to  thirty  days  as  the  pupal  period,  and  mentions  that  the  pupa  works  its 
way  out  of  the  cocoon  before  giving  forth  the  moth.  Osborn  and  Gos- 
sard have  found  the  pupa-cases  in  abundance  on  the  ground,  from 
which  a  brood  had  just  issued. 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  137 

Natural  Enemies. — We  have  reared  several  braconid  and  ichneu- 
monid  parasites  of  the  seed-caterpillar  which  await  authentic  determin- 
ation. The  following  species  have  been  published  as  parasites  of  this 
host:  the  ichneumonid  Glypta  leucozonata  Ashm.  (Proc.  U.  S.  Nat. 
Mus.,  Vol.  XII.,  1889  [1890],  p.  449),  reared  in  Missouri  by  Miss  M. 
E.  Murtfeldt;  the  braconid  Phanerotoma  (Sigalphus)  tibialis  Hald. 
(Proc.  Acad.  Nat.  Sci.,  Phila.,  Vol.  IV.,  1849  [1850],  p.  203),  raised  in 
Washington,  D.  C,  by  Comstock;  and  a  second  braconid,  Microdus 
laticinctus  Cress.  (Can.  Ent.,  Vol.  V.,  1873,  p.  53),  recorded  from 
Missouri,  Iowa,  Canada,  and  elsewhere.  In  Iowa,  Osborn  and  Gos- 
sard  have  reared  the  last  in  abundance  from  cocoons  of  the  clover 
seed-caterpillar,  and  have  found  that  it  corresponds  exactly  with  its 
host  as  regards  the  number  and  the  duration  of  the  broods. 

Gossard  expresses  the  presumption  that  the  braconid  Bracon  ver- 
noni(s  Ashm.  (Proc.  U.  S.  Nat.  Mus.,  Vol.  XL,  1888  [1889],  p.  619) 
is  a  parasite  of  E.  interstinctana  in  Iowa,  since  it  is  associated  with  the 
latter  species  in  marked  numbers  and  corresponds  closely  with  it  in 
time  of  appearance. 

Control. — The  best  remedy  for  the  attack  of  the  seed-caterpillar  is 
that  proposed  by  Comstock,  namely,  to  cut  and  store  the  hay  crop 
early  in  June  (New  York,  Illinois,  Iowa),  just  as  advised  for  the  seed- 
midge,  in  order  to  kill  the  larvae  while  still  in  the  heads.  The  hay 
should  be  handled  lightly  and  stacked  or  stored  as  soon  as  possible. 
Osborn  and  Gossard  have  attested  the  value  of  this  method,  and  have 
given  these  further  recommendations :  ( 1 )  cut  volunteer  clover  in  early 
June  and  dispose  of  the  heads  speedily;  (2)  do  not  allow  clover  to  run 
for  more  than  two  years ;  (3)  sow  seed  on  land  remote  from  old  fields ; 
(4)  pasture  clover  in  the  fall  of  the  first  year;  (5)  plow  an  old  clover 
field  under  in  October  or  November  or  in  early  spring,  then  harrow  and 
roll.  These  practices  operate  at  the  same  time  against  several  other 
clover  pests. 

Enarmonia  (Grapholitha)  interstinctana  Clem. 

1860.     Clemens,  B.— Proc.  Acad.  Nat.  Sci.,  Phila.,  p.  351. 
1881.     Comstock,  J.  H.— Rep.  U.  S.  Comm.  Agr.,  1880,  pp.  254, 
255. 

1891.  Osborn,  H.,  and  Gossard,  H.  A.— Insect  Life,  Vol.  IV., 

pp.  56-58. 
Osborn,  H.,  and  Gossard,  H.  A. — Bull.  No.  14,  Iowa  Agr. 

Exper.  Sta.,  pp.  166-169. 
Osborn,  H.,  and  Gossard,  H.  A. — Bull.  No.  15,  Iowa  Agr. 

Exper.  Sta.,  pp.  260-262. 
Osborn,   H.,   and   Gossard,   H.   A. — Twenty-second   Ann. 

Rep.  Ent.  Soc.  Ontario,  pp.  74,  75. 

1892.  Gossard,  H.  A.— Bull.  No.  19,  Iowa  Agr.  Exper.  Sta.,  pp. 

571-589.   ' 

1896.     Lintner,  J.  A.— Eleventh  Rep.  State  Ent.  N.  Y.,  pp.  152- 
156. 


138 


BULLETIN  No.  134 


[April, 


PEA-LOUSE,  OR  CLOVER-LOUSE 

Macrosiphum  pisi  Kalt. 
(Nectarophora  destructor) 

This  is  a  big,  green,  long-legged  plant-louse  that  has  ruined  mil- 
lions of  dollars'  worth  of  field  peas  and  a  great  deal  of  red  clover.     It 
is  the  dominant  species  of  its 
kind  on  these  plants  (Fig.  5) 
and  can  scarcely  be  confused 
with  any  other  aphid. 

Distribution.  —  This  pest 
was,  in  all  probability,  intro- 
duced with  clover  and  peas 
from  Europe,  where  it  is 
widely  distributed  and  com- 
mon, tho  it  is  reported  mostly 
from  England,  Germany, 
France,  and  Italy.  In  the 
United  States  it  has  been  in- 
jurious in  Maine,  New  Hamp- 
shire, Vermont,  Massachu- 
setts, Connecticut,  New  York, 
New  Jersey,  Pennsylvania, 
Delaware,  Maryland,  the  Dis- 
trict of  Columbia,  Virginia, 
North  Carolina,  Ohio,  Illinois, 
Michigan,  Wisconsin,  Minne- 
sota, Nebraska,  Iowa,  Ken- 
tucky, and  Texas.  It  is  wide- 
spread in  Canada  also,  occur- 
ring in  Nova  Scotia  and  New 
Brunswick  and  westward  thru  Ontario. 

Not  until  1899  did  the  louse  attract  the  attention  of  American 
entomologists;  in  that  year  an  outbreak  in  Maryland  was  reported 
upon  by  W.  G.  Johnson.  He  and  E.  D.  Sanderson  have  written  most 
of  the  literature  on  the  species. 

Our  personal  observations  of  several  years,  made  as  independ- 
ently as  possible,  have  yielded  many  facts  that  were  already  known 
and  many  that  are  new.  The  present  account  refers  especially  to  the 
insect  as  it  occurs  in  Illinois.  In  the  eastern  states  the  insect  is  chiefly 
a  pest  on  peas.  Here,  where  peas  are  not  grown  extensively,  it  is 
a  pest  on  red  clover. 

Food  Plants  and  Injury. — Under  the  name  of  "green  dolphin" 
this  aphid  has  long  been  known  in  Europe  for  its  injuries  to  peas  and 
vetches,  and  in  minor  measure  to  clovers  and  various  weeds — some 
forty  plants  in  all. 

In  America  the  aphid  has  done  immense  damage  to  peas  and 
clovers.  It  affects  especially  leguminous  plants,  but  numbers  also 


FIG.   5. — Clover-louse,  Macrosiphum  pisi,  on  sterns 
of  red  clover.      Natural  size. 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  139 

among  its  food  plants  many  weeds  of  diverse  families.  The  more 
important  of  its  food  plants  are  red  clover,  crimson  clover,  field 
pea,  sweet  pea,  vetches  (known  also  as  "tares"),  beet,  lettuce,  shep- 
herd's purse,  and  nettle,  not  to  mention  the  rest  of  the  weeds.  Alfalfa 
seems  to  be  immune  from  attack.  Thirty  sweeps  of  the  net  in  red 
clover  yielded  3000  of  the  aphids,  while  the  same  number  of  similar 
sweeps  in  an  adjoining  field  of  alfalfa  gave  only  30.  This  alfalfa 
was  mixed  with  some  clover,  however,  and  observations  on  the  few 
lice  that  could  be  found  on  the  alfalfa  failed  to  find  them  in  the  act 
of  feeding.  On  soy-beans  growing  next  to  heavily  infested  clover, 
not  a  single  louse  was  found.  Where  crimson  clover  is  grown,  the 
aphid  prefers  it  to  red  clover,  it  is  said. 

Where  peas  are  grown,  the  aphid  winters  in  a  field  of  clover  or 
on  weeds  (as  a  wingless  female  or  as  an  egg),  and  in  spring  is  con- 
fined to  these  until  the  peas  start  to  grow,  and  then  it  does  not  get 
to  the  early  varieties,  tho  it  devastates  the  late-sown  peas.  In  early 
spring  most  of  the  aphids  are  wingless  and  remain  where  they  happen 
to  be,  but  in  late  spring  (May  1,  Delaware)  and  early  summer  there 
are  many  winged  females  that  can  go  from  clover  to  peas  and  start  an 
infestation.  The  first  aphids  select  the  youngest  leaves  and  shoots,  but 
eventually  the  lice  cover  the  entire  plant  and  sap  out  its  life,  rendering 
it  unfit  even  for  fodder. 

In  Wisconsin  the  louse  was  noticed  in  a  five-hundred  acre  field  of 
peas  about  July  20;  in  less  than  a  week  all  the  plants  were  dead  and 
brown.  In  Maryland  in  1899,  the  louse  destroyed  peas  valued  at 
$3,000,000,  conservatively  estimated,  and  in  1900,  $4,000,000  worth 
were  destroyed. 

On  red  clover,  the  youngest  leaves  and  stems  are  the  first  to  be 
attacked,  and  these  wither  and  die  if  many  aphids  are  present.  Wilted 
leaves  mark  the  spread  of  the  pest  over  the  plant.  Red  clover,  how- 
ever, can  stand  a  good  deal  of  this  injury,  and  if  a  heavy  rain  happens 
to  occur  when  the  plant  is  covered  with  the  lice,  they  are  washed  off, 
and  the  field  is  safe  for  the  rest  of  the  season.  There  are  also  numer- 
ous insect  enemies  and  a  fungous  disease,  which  kill  off  immense  num- 
bers of  the  lice.  At  times  a  combination  of  circumstances  occurs,  how- 
ever, under  which  the  plant  is  killed,  root  and  all.  The  natural  checks 
upon  the  increase  of  the  aphid  may  be  insufficient;  but  dry  weather 
seems  to  be  the  most  important  factor.  Without  rain  the  plant  can 
not  replace  the  sap  taken  by  the  aphids,  let  alone  make  any  growth ;  in 
dry  weather  the  fungus  can  not  develop ;  and  in  the  absence  of  heavy 
rains  to  wash  them  off  the  plants,  the  aphids  thrive.  In  dry  weather, 
when  the  plants  are  loaded  with  lice,  the  cutting  of  the  clover  is  the 
last  straw. 

In  1903  the  louse  killed  an  immense  amount  of  red  clover,  and 
weakened  much  more,  in  De  Kalb  county.  Being  sent  there  by  the 
State  Entomologist,  I  found  on  the  farm  of  Mr.  A.  E.  Myers,  at  Mill- 
brook,  August  19,  eighty  acres  of  dead  clover  roots  in  one  field.  Not 
one  root  in  a  thousand  showed  any  signs  of  life,  and  on  the  ground 
were  thousands  of  the  cast  skins  of  the  aphid.  At  cutting,  the  lice  had 


140  BULLETIN  No.  134  [April. 

been  such  a  nuisance  that  the  men  objected  to  handling  the  crop.  After 
cutting,  the  clover  never  revived.  In  neighboring  fields  there  were 
many  bare  spots  where  the  aphid  had  killed  the  clover  locally,  and  in 
the  growing  clover  were  many  centers  of  new  infestation,  due  doubt- 
less to  migrant  winged  females.  All  the  clover  in  that  part  of  the 
county  was  more  'or  less  injured;  not  only  old  clover,  but  also  the  first- 
year  growth.  Returning  to  the  same  region  the  following  summer,  to 
see  the  consequences  of  the  injury,  I  did  not  stay  long,  for  it  was  hard 
to  find  a  field  of  clover  anywhere.  The  farmers  reported  that  the 
clover  had  been  "winter-killed,"  to  their  surprise,  since  the  winter  had 
not  been  a  severe  one  and  the  clover  had  often  survived  worse  winters. 
The  failure  of  the  clover  had  discouraged  almost  all  of  them  from 
sowing  a  new  crop.  My  personal  opinion  was  that  the  "winter-killing" 
would  not  have  occurred  had  not  the  plants  been  weakened  previously 
by  the  aphid.  Clover  is  undoubtedly  injured  by  certain  winter  influ- 
ences, especially  by  being  "heaved"  out  of  the  ground  by  frost,  but 
there  must  be  taken  into  consideration  also  the  inability  of  the  plant  to 
face  the  winter  when  it  has  been  ravaged  by  such  insects  as  the  aphid 
or  the  root-borer. 

Only  at  rare  intervals t  has  there  been  a  bad  outbreak  of  this  spe- 
cies. In  England,  according  to  Kirby  and  Spence,  the  havoc  wrought 
by  this  aphid  in  1810  was  remarkable  for  its  suddenness.  Equally  un- 
anticipated was  the  outbreak  of  1899  in  some  of  the  Atlantic  states 
and  in  Canada.  In  1900  the  devastation  continued  in  places  where  the 
previous  injury  had  been  worst,  and  a  new  outbreak  occurred  in  Wis- 
consin. Since  then  no  reports  of  serious  damage  have  been  published, 
but  in  Illinois  this  aphid  was  locally  injurious  in  1903,  as  just  de- 
scribed, and  has  menaced  the  red  clover  every  year  from  1903  up  to 
the  present.  Heavy  rains  subdue  the  louse  almost  every  year. 

Description. — The  clover-louse  is  noticeably  larger  than  any  of 
the  other  aphids  that  frequent  the  field,  the  largest  females  being  6  mm. 
from  tip  to  tip.  The  green  color  of  the  louse  matches  that  of  its  food 
plant.  The  legs  are  conspicuously  long,  and  the  tarsi,  distal  ends  of 
the  tibiae  and  femora,  as  well  as  the  tips  of  the  cornicles,  are  fuscous. 
The  antennae  are  darker  at  the  joints,  with  the  terminal  filament  fus- 
cous. The  eyes  are  red  and  prominent.  With  this  general  statement 
we  may  pass  to  a  more  detailed  description  of  the  species. 

The  generic  term  Nectarophora  is  antedated  by  Macrosiphum 
(Pergande,  Bull.  44,  Div.  Ent,  U.  S.  Dept.  Agr.,  pp.  13,  14). 

With  the  other  species  of  its  genus,  M.  pisi  has  the  front  of  the 
head  concave,  with  a  large  pair  of  tubercles  supporting  the  antennas. 
The  antennas,  legs,  cornicles,  and  abdominal  stylus  are  exceptionally 
long  in  this  genus  as  compared  with  other  genera  of  aphids.  The  wings 
are  large,  the  third  discoidal  vein  has  two  forks,  and  the  stigma  is 
elongate-lanceolate.  The  terminal  po'rtion  of  the  sixth  antennal  seg- 
ment is  very  long  and  bristlelike.  Most  of  the  species  of  Macrosiphum 
are  large  and  frequent  herbage. 

On  the  basis  of  Sanderson's  studies  we  are  obliged  to  regard  this 
aphid  (the  N.  destructor  of  Johnson)  as  the  common  M.  pisi,  of  Eu- 
rope, described  long  ago  by  Kaltenbach. 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  141 

The  alate  viviparous  female  (PI.  II.,  Fig.  1)  is  4  to  5  mm.  long, 
with  an  occasional  maximum  of  6.  mm.,  and  1  to  1.5  mm.  broad.  An- 
tennae long,  reaching  to  the  tip  of  the  stylus  or  a  little  beyond;  first 
and  second  segments  short  and  close  to  the  tubercle;  third  to  sixth 
segments  related  in  length  respectively  as  3:2:  1.5:4,  the  terminal  fila- 
ment of  the  sixth  segment  being  three  times  as  long  as  the  base.  Wing 
expanse  about  1 1  mm.  Fore  wing  5  mm.  by  2  mm.  Cornicles  slender, 
cylindrical,  and  long, — 1  to  1.5  mm.  Abdominal  stylus  half  as  long  as 
the  cornicles. 

Sanderson  gives,  smaller  measurements  thruout  for  the  autumn 
winged  viviparous  female,  it  being  only  3.15  mm.  in  length,  with  pro- 
portions varying  a  little  from  those  just  given. 

The  apterous  viviparous  female  (PI.  II.,  Fig.  2)  is  a  little  larger 
than  the  winged  female,  ranging  in  length  from  4  to  6  mm.,  and  the 
body  is  more  elongate  and  fusiform,  with  longer  cornicles  (1.25  to  2 
mm.)  and  a  longer  stylus.  This  form  also  is  smaller  in  autumn,  as 
Sanderson  has  noted,  with  much  more  extensive  dark  brown  or  black- 
ish markings  on  the  appendages. 

The  oviparous  female  is  apterous. 

The  egg  has  not  been  described  before.  It  is  elliptical,  twice  as 
long  as  broad  (0.5  mm.  by  0.25  mm.),  and  changes  from  saffron-yellow 
to  shiny  black  one  or  two  days  after  being  laid. 

The  winged  male  is  2.5  mm.  in  length,  with  a  wing  expanse  of  9 
mm.  It  may  be  recognized  by  its  smaller  size,  among  other  things.  The 
color  tends  toward  pale  green  or  yellow.  The  dorsal  sclerites  are  dark, 
as  is  also  the  mesosternum,  and  there  are  lateral  blackish  spots  in  front 
of  the  cornicles.  Sanderson  has  described  this  form. 

Our  insectary  notes  on  one  pair  of  M.  pisi  taken  in  coitu  refer  to 
the  male  as  being  apterous. 

In  autumn  many  of  the  aphids  normally  turn  yellow;  in  fact, 
some  yellow  individuals  can  be  found  at  any  time,  and  aphids  that  are 
diseased  usually  do  become  yellow. 

Life  History. — The  clover-louse  winters  both  as  a  large  wingless 
viviparous  female  and  as  an  egg,  but  the  eggs  are  not  numerous. 
Many  of  the  females  are  killed  off  during  the  winter.  The  survivors 
are  easily  found  under  rubbish  in  the  clover  field  in  the  first  week 
of  April  and  even  as  early  as  March  25,  tho  they  are  a  little  slow  to 
revive.  They  crawl  to  the  clover  plants  and  proceed  to  suck  the  sap 
and  to  bring  forth  living  young,  all  of  which  are  also  females ;  indeed, 
no  males  appear  until  the  last  of  the  season  and  no  eggs  are  laid  until 
then.  During  most  of  the  season  there  is  nothing  but  a  constant  suc- 
cession of  females,  all  of  them  born  alive.  Most  of  them  are  wingless, 
tho  in  any  of  the  generations  there  may  be  some  females  that  have 
wings;  these  also  bear  their  young  alive. 

The  eggs  that  were  laid  on  green  leaves  or  stems  the  preceding  au- 
tumn hatch  a  few  days  after  the  red  clover  starts  on  its  new  growth. 
March  23  Mr.  E.  O.  G.  Kelly  found  newly  hatched  young  on  a  clover 
plant,  and  egg-shells  close  by  on  old  dead  clover  leaves.  One  of  these 
aphids,  kept  on  potted  clover,  produced  her  first  young  April  5,  and 
died  May  12,  after  having  brought  forth  ninety -young. 


142 


BULLETIN  No.  134 


[April, 


Mr.  R.  L.  Webster  carried  thru  the  season  successive  generations 
derived  from  a  single  female  that  came  from  the  egg  March  23,  and 
obtained  (by  breeding  always  from  the  first-born)  as  many  as  seven- 
teen generations,  the  young  of  the  seventeenth  brood  issuing  Septem- 
ber 21  to  October  3.  In  the  field,  newly  born  young  can  be  found  as 
late  as  November  4,  tho  we  can  not  name  the  generation  to  which  they 
belong.  His  more  important  data  may  best  be  given  in  the  form  of  a 
table. 

M.  pisi 


Genera- 
tion 

Birth 

Maturity 

Death 

Days  to 
mature 

Days  of 
life 

Number 
of  young 

1 

Mar.  23 

Apr.  5 

May  12 

13 

50 

90 

2 

Apr.  5 

Apr.  25 

May  12 

20 

37 

87 

3 

Apr.  26 

May  8 

May  13 

12 

17 

25 

4 

May  8 

May  20 

June  16 

12 

39 

89 

5 

May  20 

May  31 

June  9 

11 

20 

49 

6 

June  1 

June  10 

June  20 

9 

19 

41 

7 

June  10 

June  19 

July  17 

9 

37 

37 

8 

June  19 

July  1 

July  17 

12 

28 

60 

9 

July  1 

July  10 

Aug.  2 

9 

32 

63 

10 

July  12 

July  22 

Aug.  3 

10 

22 

30 

11 

July  22 

Aug.   3 

Aug.  15 

12 

24 

44 

12 

Aug.   3 

Aug.   11 

Aug.  16 

8 

13 

34 

13 

Aug.   11 

Aug.  21 

Aug.  30 

10 

19 

16 

14 

Aug.  21 

Sept.  1 

Sept.  5 

11 

15 

8 

15 

Sept.  2 

Sspt.  12 

Sept.  15 

10 

13 

10 

16 

Sept.  12 

Sept.  21 

Oct.  4 

9 

22 

S3 

Ave 

rapes 

11 

25.4 

46 

The  averages  are  worth  notice.  A  female  begins  to  reproduce 
eleven  days  after  birth,  as  a  rule;  this  accounts  for  the  large  number 
of  generations.  The  average  number  of  young  is  not  large  for  an  in- 
sect, for  insects  as  a  whole  average  at  least  two  or  three  hundred  eggs 
per  female.  The  average  given  in  the  table  is  confirmed  by  one  based 
upon  a  large  number  of  additional  observations  taken  thruout  the 
season.  A  female  is,  however,  capable  of  producing  as  many  as  147 
young,  and  many  of  the  females  at  death  have  embryos  of  various 
stages  in  their  bodies. 

The  largest  number  of  young  produced  in  one  day  by  one  female 
is  13,  and  the  average  number  6,  in  our  experience ;  while  the  bearing- 
period  of  the  female  averages  12.1  days.  In  October  and  November  the 
females  bear  but  few  young,  but  some  of  these  females  hibernate  and 
produce  more  young  the  following  year. 

Our  breeding  experiments,  it  should  be  said,  were  conducted  in- 
doors, where  the  aphids  were  protected  from  every  source  of  danger. 
Out-of-doors  the  mortality  would  probably  not  be  so  small. 

R.  L.  Webster's  continuous  observations  on  the  life  history  are  a 
useful  addition  to  our  knowledge  of  the  species.  His  results  are  cor- 
roborated by  those  of  Mr.  E.  Q.  Snider,  who,  while  a  student  at  the 


1909] 


THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA 


143 


University  of  Illinois,  made  a  similar  series  of  studies.  He  began  with 
the  first  hibernating  females  that  he  could  find,  and  traced  their 
progeny.  One  of  the  females  found  April  8  brought  forth  the  first 
young  aphid  April  17,  and  this  acquired  wings  April  29.  In  the  field  I 
have  seen  winged  individuals  at  all  times  up  to  November  10. 

Five  apterous  viviparous  females  studied  by  Snider  bore,  respect- 
ively, before  the  end  of  June,  104,  108,  110,  124,  and  147  young.  The 
last  number  is  unusually  large  even  for  an  aphid. 

Males  and  oviparous  females  were  not  found  until  October  (with 
one  exception — a  female  born  September  22)  ;  and  males  were  taken  in 
the  field  October  10,  17,  20,  and  November  3.  Copulation  was  observed 
in  the  field  October  20  and  November  3 ;  in  the  last  instance  oviposi- 
tion  began  twenty-five  minutes  after  copulation  ceased.  Six  females 
began  to  oviposit,  respectively,  October  18,  20,  21,  31,  and  November 
3  and  4.  One  female  in  coitu  October  20  laid  eggs  October  26  (2 
eggs),  29  (1),  31  (2),  November  3  (1),  4  (1),  5  (1),  6  (2),  18  (2), 
and  no  more  up  to  December  2,  when  the  observations  ended.  A  fe- 
male born  September  22  laid  an  unfertilized  egg  October  18.  A  female 
taken  in  the  field  October  11,  1904,  laid  eggs  October  21,  which  hatched 
March  23,  1905.  The  eggs  have  escaped  the  notice  of  previous  ob- 
servers. Here,  the  eggs  are  common. 

Habits. — When  these  aphids  are  as  yet  few,  they  select  the  young- 
est leaves  and  stems  of  the  plant,  especially  the  under  sides  of  the 
leaves;  but  as  they  increase,  they  spread  over  the  plant,  and  may 
crowd  together  so  closely  that  large  numbers  fall  to  the  ground  for 
want  of  standing  room. 

The  rapid  increase  in  the  number  of  individuals  is  not  due  to  any 
extraordinary  prolificacy,  but  results  from  the  rapid  growth  and  conse- 
quent early  maturity  of  each  aphid  and  from  the  fact  that  almost  every 
individual  is  a  female. 

While  the  aphid  is  growing,  the  moults  occur  at  short  but  variable 
intervals,  as  appears  in  the  following  table  made  from  R.  L.  Webster's 
notes. 

'M.  pisi 


No.  of 

genera- 
tions 

Born 

First 
moult 

Second 
moult 

Third 
moult 

Fourth 
moult 

First 
young 

1 

March  23 

March  28 

March  31 

April  2 

•     April  4 

April  5 

1 

March  23 

March  25 

March  31 

April  4 

April  9 

2 

April  5 

April  9 

April  12 

April  15 

April  21 

April  25 

2 

April  5 

April  10 

April  13 

April  18 

April  21 

April  26 

3 

April  26 

April  29 

May  1 

May  3 

May  5 

May  8 

4         ;  May  8 

May  12 

May  15 

May  20 

5 

May  20 

May  22 

May  23 

May  25 

May  28 

May  31 

6 

June  1 

June  3 

June  5            June  7 

June  9 

June  10 

7 

June  10 

June  12 

June  13 

June  15 

June  17 

June  19 

9 

Julyl 

JulyS 

July  4 

July  6 

July  7 

July  10 

9 

Julyl 

July3 

JulyS 

July  6 

July  10 

July  11 

144  BULLETIN  No.  134  [April, 

Thus  there  are  four  moults,  or  five  instars,  and  the  mother  does 
not  reproduce  until  after  the  last  moult. 

Another  student  (J.  P.  Gilbert)  found  five  moults  in  one  instance: 
an  isolated  female,  born  June  20,  moulted  June  23,  26,  27,  29,  and  30. 
Each  cast  skin  was  removed  as  soon  as  found,  and  five  of  them  were 
found. 

More  interesting  than  the  number  of  moults  is  the  fact  that  the 
females  reproduce  for  many  successive  generations  without  the  aid  of 
the  male— -a  normal  phenomenon  among  aphids,  and  many  other  in- 
sects as  well — and  also  the  fact  that  the  young  are  born  alive.  This 
can  easily  be  witnessed,  as  aphids  are  so  numerous.  In  this  species 
the  young  aphid  emerges  hind  end  first  and  back  upward,  and  envel- 
oped in  a  delicate  membrane,  which  it  gets  rid  of  by  means  of  vigorous 
kicking.  The  entire  process,  requiring  ten  or  fifteen  minutes,  is  essen- 
tially as  described  elsewhere  and  in  more  detail  for  other  species. 

The  mother  does  not  wander  much  after  beginning  to  reproduce, 
but  stays  in  one  spot,  with  the  younger  of  her  progeny  clustered 
around  her. 

The  winged  females,  which  may  occur  in  any  of  the  seventeen  or 
more  generations,  are  the  chief  means  of  spreading  the  specie^.  They 
are  feeble  of  flight,  but  are  often  assisted  by  the  wind  to  reach  distant 
places. 

Fertilization  is  evidently  essential  to  the  production  of  an  egg 
that  will  hatch,  tho  eggs  are  laid  whether  fertilization  has  occurred  or 
not.  The  deposition  of  an  egg  requires  about  seven  minutes,  as  noted 
by  E.  O.  G.  Kelly,  who  observed  also  that  the  female  used  her  hind 
legs  to  assist  the  egg  out.  A  fluid  that  accompanies  the  egg  serves  to 
glue  it  to  a  green  leaflet,  on  either  side  of  which  the  egg  may  be  laid. 
The  eggs  remain  over  winter  on  the  dead  leaves  or  stems  on  the 
ground. 

In  November  there  are  still  many  mature  females  in  the  field,  and 
they  feed  on  mild  days,  crawling  under  shelter  when  the  weather  turns 
cold.  If  clover  sod  is  brought  indoors  during  the  winter,  the  females 
appear  with  the  new  growth  and  the  plants  soon  become  overrun  with 
aphids.  Out-of-doors,  most  of  the  hibernating  females  meet  their 
death  sooner  or  later  during  the  winter,  in  this  region,  notwithstanding 
the  fact,  reported  by  W.  G.  Johnson,  that  the  species  can  survive 
severe  freezing. 

Natural  Enemies. — The  most  important  enemy  of  this  louse  is  a 
common  fungus,  Empusa  aphidis.  It  is  wide-spread  in  the  United  States 
and  Canada,  and  affects  a  great  variety  of  aphids,  its  abundance,  when 
it  occurs,  being  proportional  to  that  of  its  host.  It  does  not  appear  in 
dry  weather  but  is  common  after  a  rain  or  two  at  any  time  during  the 
growing  season,  and  is  most  abundant  under  the  combined  influences 
of  moisture  and  warmth.  Then  it  sweeps  off  myriads  of  aphids. 
Those  killed  by  the  epidemic  remain  clinging  to  the  plant  in  a  more  or 
less  lifelike  attitude,  but  turn  yellow  and  then  light  brown,  become 
swollen,  and  eventually  coated  with  the  fungus  (PI.  II.,  Fig.  3).  The 


1909] 


THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA 


145 


appearance  of  the  insect  is  at  first  similar  to  that  caused  by  the  pres- 
ence of  a  larval  Aphidius  in  the  body  of  the  aphid.  The  parasite, 
however,  at  length  spins  a  silken  cocoon  under  the  aphid,  and  when- 
ever present  can  easily  be  found  by  dissection. 

The  life  history  of  this  fungus  is  like  that  of  E.  sphcerosperma,  as 
given  in  some  detail  in  the  account  of  the  clover  leaf-weevil,  and  is 
discussed  at  length  by  Thaxter  in  the  Memoirs  of  the  Boston  Society 
of  Natural  History,  Vol.  IV.,  1888,  pp.  175-177. 

Macrosiphum  pisi  is  affected,  directly  or  indirectly,  by  a  large 
number  of  other  insects,  of  which  other  writers  have  recorded  twenty. 
These  and  thirteen  additional  species  are  listed  below. 


Gryllida 

CEcanthus  confluens  H.  &  H. 

MS. 
Pentatomidce 

Podisus  maculiventris  Say 
(=  spinosus  Dall.) 

Euschistus  variolarius  P.  B. 
Acanthiidce 

Triphleps  insidiosus  Say 
Chrysopidce 

Chrysopa  oculata  Say 

Chrysopa  rufilabris  Burm. 

Chrysopa  plorabunda  Fitch 
Syrphidce 

Ocyptamus  '(Baccha)    fusci- 
pennis  Say 

Platychirus  quadratus  Say 

Syrphus  americanus  Wied. 

Syrphus  ribesii  L. 

Allograpta  obliqua  Say 

Mesogramma   marginatu'm 
Say 

Mesogramma  politum  Say 

Sphserophoria  cylindrica  Say 
Ichneumonidce 

Bassus  Isetotorius  Fab. 


Coccinellidce 

Megilla  maculata  DeG. 

Hippodamia  glacialis  Fab. 

Hippodamia  convergens  Guer. 

Hippodamia    tredecimpuncta- 
ta  L. 

Hippodamia  parenthesis  Say 

Coccinella  novemnotata  Hbst. 

Coccinella  sanguinea  L. 

Adalia  bipunctata  L. 

Chilocorus  bivulnerus  Muls. 
Lampyridce 

Podabrus  rugulosus  Lee. 
Cecidomyiidce 

Diplosis  sp. 
Braconidce 

Perilitus  americanus  Riley 

Trioxys  (Praon)  cerasaphis 
Fitch 

Aphidius  fletcheri  Ashm.  MS 

Aphidius      washingtonensis 

Ashm.  MS. 
Chalcididce 

Isocratus  vulgaris  Walk. 

Pachyneuron  syrphi  Ashm. 
Acarina,  Rhyncholophidce 

Rhyncholophus  parvus  Banks 


Most  of  these  species  I  have  studied  in  Illinois  in  their  relation 
to  M.  pisi.  Below  is  a  summary  of  all  that  we  know  on  the  subject 
up  to  the  present  date.  All  these  insects,  concerned  in  one  way  or 
another  with  the  clover-louse,  are  either  predaceous  or  parasitic. 

Coccinellidce. — The  omnipresent  ladybird  beetles  and  their  larvae 
are  in  this  region  the  most  efficient  of  the  insect  enemies  of  the  clover- 
louse.  The  larvae  in  particular  destroy  the  louse  in  immense  numbers. 
They  are  by  no  means  limited  to  this  aphid,  but  when  it  predominates, 
the  number  of  Coccinellidce  present  is  a  good  measure  of  the  abun- 
dance of  the  louse. 


146 


BULLETIN  No.  134 


[April, 


FIG.  6. — Ladybird,  Megilla  maculata:  a,  larva;  b,  empty 
pupal  skin;  c,  beetle.  (Chittenden,  Circ.  43,  Bur.  Ent., 
U.  S.  Dept.  of  Agriculture.) 


The  hemispherical,  brightly  colored  ladybird  beetles  (Fig.  6)  are 
familiar,  tho  their  larvae  are  not  so  generally  recognized.  The  ento- 
mologist knows  them  as 
active  little  alligator-like 
creatures,  with  a  long 
warty  or  spiny  abdomen. 
Some  of  them  are  black- 
ish, but  most  of  the  com- 
mon kinds  are  spotted 
with  conspicuous  colors. 
The  pupa  is  attached  by 
the  tail  to  a  silken  support 
spun  by  the  larva  on  a 
green  leaf  or  other  object. 
Its  period  is  four  to  eight 
days,  usually  five  or  six  in 
July,  in  the  case  of  several 
of  our  common  species.  The  yellow  elliptical  eggs,  laid  in  small  clus- 
ters, are  conspicuous  on  green  leaves  and  elsewhere. 

Coccinellidce  in  general  hibernate  as  beetles,  and  all  the  species 
mentioned  here  do  so.  They  are  among  the  first  insects  to  appear  in 
the  warm  days  of  late  March  and  early  April.  Comparatively  few  at 
the  opening  of  the  season,  they  multiply  rapidly,  tho  in  this  respect 
they  lag  somewhat  behind  the  plant-lice  on  which  they  feed,  if  the 
latter  are  at  all  numerous.  Coccinellidce  feed  also  on  scale  insects, 
pollen  grains,  spores,  etc.,  as  Forbes  found  (Bull.  No.  6,  111.  State  Lab. 
Nat.  Hist.,  1883,  pp.  33-64),  but  feed  chiefly  on  plant-lice,  and  thus 
are  beneficial. 

Adalia  bipunctata  and  Hippodamia  glacialis  were  not  often  met 
with  in  the  clover  field,  and  Coccinella  sanguined  was  not  numerous. 
Chilocorus  bivulnerus,  well  known  as  a  destroyer  of  scale  insects,  was 
rather  common  at  times  as  an  enemy  of  the  clover-louse.  The  other 
species  listed  above  were  always  common.  C.  g-notata  we  noted  as 
emerging  as  a  beetle  June  29,  July  16  and  18 ;  C.  sanguined,  June  23 ; 
H.  ij-punctata,  July  15,  16,  and  18;  M.  maculata,  June  20,  21,  22, 
and  24;  H.  parenthesis  issued  July  1,  2,  and  5,  from  pupae  found  June 
27 ;  and  eggs  of  this  species,  found  June  14,  hatched  June  20,  one  of 
the  larva?  pupating  July  11  and  giving  the  beetle  July  15. 

All  the  species  listed  were  actually  seen  feeding  upon  M.  pisi, 
ejther  in  the  field  or  in  the  insectary.  In  the  latter  place,  the  diet  of 
three  Megilla  maculata  beetles  included  also  (to  their  discredit)  one 
coccinellid  pupa,  one  adult  C.  sanguinea  and  two  beetles  of  their  own 
kind,  besides  some  of  their  own  eggs  and  (to  their  credit)  eggs  of  the 
Colorado  potato-beetle  that  were  offered  to  them. 

Perilitus  americanus,  a  braconid  parasite  of  the  beetle  of  Megilla 
maculata  and  now  and  then  of  C.  p-notata,  we  reared  several  times 
from  the  former  host.  Parasitized  beetles  taken  on  clover  leaves  June 
17,  gave  the  winged  braconid  June  21  and  22;  others,  of  June  23,  gave 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  147 

the  adults  June  30.  My  own  experience  with  the  parasite  leads  me  to 
take  no  exception  to  the  accounts  already  published  by  Riley  (Insect 
Life,  Vol.  I.,  pp.  101-104,  338,  339)  and  by  Weed  and  Hart  (Psyche, 
Vol.  V.,  pp.  188-190).  Briefly,  it  may  be  said  the  beetle  is  found 
standing  on  a  leaf  and  looking  quite  natural ;  indeed,  it  can  still  move 
some  part  of  itself  in  most  instances,  tho  it  can  not  move  away  from 
the  spot,  for  it  is  held  by  its  feet  to  a  brown  mass  of  silk — a  cocoon, 
from  which  the  parasite  will  emerge  in  its  winged  form.  The  beetle 
may  remain  alive  in  this  condition  for  two  weeks  and  doubtless  a 
little  longer,  but  when  disentangled  from  its  foothold  it  is  unable  to 
move  its  legs  in  coordination — is  unable  to  walk. 

The  larva  that  made  the  cocoon  has  issued  from  the  beetle  and 
could  previously  have  been  found  inside  the  host,  but  some  mystery 
exists  as  to  where  the  larva  makes  its  exit,  for  the  shell  of  the  beetle 
appears  to  be  unbroken. 

This  Perilitus,  then,  is  a  check  upon  the  beneficial  ladybird  beetle, 
but  is  of  no  practical  importance  on  account  of  its  infrequency. 

On  many  occasions  I  have  seen  adults  of  Podisus  maculiventris 
(spinosus)  and  Euschistus  variolarius  sucking  the  pupae  of  various  of 
the  coccinellids  that  prey  upon  the  clover-louse.  The  eggs  of  both 
these  pentatomids  are  heavily  parasitized  by  a  proctotrypid. 

Syrphidce. — Among  the  commonest  insects  of  the  clover  field  are 
several  species  of  Syrphida,  or  flower-flies  (Fig.  7,  8),  some  of  which 
are  known  also  as  "sweat  bees."  Many  of  these  flies  are  banded  with 
black  and  yellow,  and  have  the  habit  of  poising  over  this  or  that  spot 
for  a  few  moments  and  making  short  dashes  from  one  place  to  another. 
The  flies  lay  their  eggs  in  or  near  colonies  of  plant-lice,  upon  which 
the  larvae  are  to  feed.  The  larvae  are  leechlike  in  form,  and  generally 
green,  yellow,  or  mottled  brownish  in  color.  They  are  often  seen 
among  the  aphids,  which  they  destroy  at  a  rapid  rate.  The  syrphid 
larva  seizes  an  aphid  between  its  hooklike  jaws,  holds  it  aloft  and 
sucks  the  blood  from  the  body,  meanwhile  waving  itself  to  and  fro. 
When  full  grown,  the  larva  shortens  and  its  skin  hardens  into  a  brown 
pear-shaped  or  elongate  puparium,  from  which  the  fly  will  issue. 

In  this  region  the  flies  are  seldom  noticed  in  the  clover  field  be- 
fore the  latter  part  of  April,  but  are  abundant  by  the  last  of  May. 
The  larvae  grow  rapidly,  and  there  are  several  generations  of  the  com- 
mon species  each  year. 

In  Maryland,  Johnson  found  the  syrphid  larvae  to  be  the  most  im- 
portant of  the  insect  enemies  of  M.  pisi,  which  they  nearly  extermi- 
nated in  some  localities.  One  pea  grower  sieved  out  twenty-five  bush- 
els of  syrphid  larvae  in  a  few  days. 

Allograpta  obliqua  Say,  he  found  to  be  by  far  the  most  common 
and  most  important  species,  forming  the  greater  bulk  of  the  twenty- 
five  bushels  mentioned.  He  refers  to  the  larvae  as  being  pea-green, 
slightly  streaked  with  white,  and  one  quarter  to  one  third  of  an  inch 
in  length  when  full  grown.  The  puparium  is  usually  found  on  a  leaf 
or  stem,  rarely  on  the  ground. 


148 


BULLETIN  No.  134 


[April, 


Sanderson,  in  Delaware,  found  almost  all  the  puparia  of  Allo- 
grapta  obliqua  to  be  parasitized  by  Bassus  latotorius  Fab.,  and  from 
several  puparia  which  seemed  to  have  been  parasitized  by  the  Bassus 
were  bred  the  chalcid  Pachyneuron  syrphi  Ashm.  B.  latotorius  is  also 
parasitized  by  Isocratus  vulgaris  Walk.,  according  to  Fletcher. 

A.  obliqua  is  a  common  species  in  Illinois,  where  the  larva  feeds 
on  M.  pisi  as  well  as  on  other  aphids. 

Syrphus  americanus  Wied.,  one  of  the  largest  species  of  the 
family,  has  conspicuous  bands  of  black  or  yellow,  and  buzzes  like  a  bee 
when  on  the  wing.  The  larva  is  greenish  or  mottled  brownish,  at- 
tains a  length  of  half  an  inch  or  more,  and  pupates  on  the  plant  or 
a  little  below  the  surface  of  the  ground,  as  Johnson  noted.  The 
species  deposits  a  single  small  oval  white  egg  in  a  colony  of  plant-lice, 
and  one  of  the  larvae  has  been  observed  to  eat  twenty-five  plant-lice  in 
as  many  minutes,  according  to  Sanderson.  In  Delaware,  he  found  it 
to  be  extremely  abundant  as  an  enemy  of  M.  pisi ;  in  Illinois,  it  feeds 
on  the  same  species  and  is  frequent  but  not  conspicuously  numerous. 

Syrphus  ribesii  L.  is  reported  from  Canada,  by  Fletcher,  as  an 
abundant  foe  of  the  aphid,  and  as  being  attacked  by  Bassus  latotorius, 
which,  in  turn,  falls  prey  to  the  chalcid  Isocratus  vulgaris.  S.  ribesii 
occurs  with  us,  but  I  have  never  happened  to  take  it  in  the  clover  field. 

Sphcerophoria  cylindrica,  a  small  syrphid  named  by  others  as 
affecting  M.  pisi,  is  rather  common  here  in  aphid-infested  clover  fields. 

Mesogramma  politum  (Fig.  7,  8)  is  frequent  in  our  clover  fields, 
the  green  larva  feeding  on  the  clover-louse.  A  full-grown  larva  found 
on  the  ground  March  27,  made  its  puparium  the  same  day,  and  the  fly 
issued  indoors  April  8. 


FIG.  7. 


Syrphus-fly,  Mesogramma  politum:   Fig.   7,   adult;     Fig.   8   (a),   larva, 
(b)  puparium.      (Riley  and  Howard,   U.   S.   Dept.   of  Agriculture.) 

Mesogramma  marginatum  has  similar  habits  and  is  common.  A 
puparium  found  on  a  clover  leaf  June  21  yielded  the  adult  June  22. 

Platychirus  quadratus,  a  small  and  frequent  species,  and  the  less 
common  Ocyptamus  fuscipennis,  I  have  taken  in  sweepings,  along  with 
the  abundant  M.  pisi.  It  is  probable  that  their  larvae  feed  on  the 
clover-louse. 


1909] 


THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA 


149 


Various  syrphid  larvae  that  destroy  M.  pisi  are  themselves  attacked 
by  Podisus  macidiventris  (spinosus)  and  Euschistus  variolarius ;  and 
the  eggs  of  these  pentatomids  are  parasitized  by  a  proctotrypid,  Teleno- 
mus  podisi  Ashm.  (determined  by  A.  A.  Girault). 

Chrysopida. — A  few  species  of  Chrysopa  (Fig.  9)  are  common  in 
the  clover  field.  The  adults,  known  as  lace-wing  flies,  are  green  or 
less  often  yellow,  with  golden  eyes  and  four  similar  gauzy  wings,  finely 
netted  with  veins.  A  few  species  have  a  characteristic  odor — C.  ocu- 
lata,  for  example.  By  day  the  flight  is  rather  sluggish,  but  toward 
evening  the  lacewings  become  more  alert ;  they  often  fly  to  a  light  at 
night.  Most  of  the  species  hibernate  as  pupae,  so  far  as  is  known,  but 
plorabunda  winters  as  an  adult.  We  have  often  found  it  hibernating 
under  dead  leaves ;  then  the  insect  is  brown  in  color.  Our  species  lay 


FIG.  9. — Lace-wing  Fly,  Chrysopa  oculata:  a,  eggs;  b,  larva;  c,  foot  of  same;  d,  larva 
devouring  pear-tree  Psylla;  e,  cocoon;  f.  adult;  g,  head  of  same;  h,  adult,  natural  size. 
(Chittenden,  Circ.  43,  Bur.  Ent,  U.  S.  Dept.  of  Agriculture.) 

their  eggs  each  at  the  tip  of  a  long  stiff  thread  and  always  in  the  vicin- 
ity of  plant-lice,  which  are  the  chief  food  of  the  larvae.  In  clover 
fields  the  eggs  are  common  on  leaves  or  stems,  and  the  larvae  eat  raven- 
ously M.  pisi  and  other  aphids,  and  eat  one  another  now  and  then, — 
particularly  when  a  lot  of  them  issue  at  the  same  time  from  one  cluster 
of  eggs.  The  prey  is  seized  between  the  points  of  the  long,  tapering 
mandibles  of  the  aphis-lion  and  the  blood  is  sucked  back  thru  a  chan- 
nel made  by  a  groove  along  the  inner  face  of  the  mandible,  against 
which  the  maxilla  fits,  to  form  a  closed  channel.  A  newly  born  larva, 


150  BULLETIN  No.  134  [April, 

unless  cannibalistic,  selects  for  its  first  meal  a  small  tender  aphid ; 
under  the  microscope,  one  can  see  the  watery  juices  of  the  victim  bub- 
bling along  the  transparent  jaws  of  the  captor.  These  larvae  are  active 
creatures,  gray,  yellowish,  or  brownish  in  color,  tho  colorless  at  birth. 
They  grow  rapidly,  and  in.  one  to  three  weeks  spin  a  silken  cocoon  by 
means  of  glands  opening  into  the  rectum.  The  cocoon,  spherical  or 
oval,  shows,  after  the  emergence  of  the  adult,  a  circular  lid. 

The  Chrysopa  larvae  are  undoubtedly  important  checks  on  the 
clover-louse.  In  red  clover  I  have  found  three  species,  namely,  ocu- 
lata,  plorabunda,  and  rufilabris.  The  last  was  not  common ;  but  the  first 
two  were  numerous,  and  their  larvae  were  frequently  seen  feeding  on 
M.  pisi,  upon  which  we  reared  them  in  the  insectary. 

A  larva  of  oculata,  taken  July  7,  spun  July  10  or  11  and  gave  the 
adult  July  27. 

A  larva  of  plorabunda  gave  precisely  the  same  record.  A  second 
larva  of  this  species,  taken  in  a  colony  of  M.  pisi,  spun  July  10,  in  a 
bent  leaflet,  the  adult  issuing  July  20. 

C.  rufilabris  emerged  July  24  from  a  cocoon  found  on  a  clover 
leaf  July  20. 

We  have  reared  no  parasites  of  Chrysopa,  but  others  have  ob- 
tained from  cocoons  of  this  genus  many  species  of  chalcids  and  a  few 
ichneumonids,  and  from  the  eggs  one  proctotrypid. 

The  most  important  of  the  predaceous  foes  of  the  clover-louse  be- 
long to  the  three  families  just  discussed.  There  remain  to  be  treated, 
several  predaceous  species  of  more  or  less  importance. 

While  the  seed-midge  works  havoc  in  the  clover  heads,  another 
member  of  the  same  family  is  busily  engaged  in  reducing  the  numbers 
of  the  clover-louse,  at  least  in  Canada,  for  all  that  we  know  about  this 
helpful  but  undetermined  species  of  Diplosis  is  what  Dr.  Fletcher 
learned  at  Ottawa,  where  in  1900  it  was  by  far  the  most  inveterate 
enemy  of  M.  pisi  on  pea-vines.  These  minute  orange  maggots  would 
transfix  an  aphid,  hold  it  up,  and  suck  out  the  blood,  in  much  the  same 
way  as  the  syrphid  larvae.  Their  growth  was  so  rapid  as  to  result  in 
several  generations  during  the  season.  Winter  was  passed  in  a  minute 
cocoon,  spun  on  the  stem  of  the  plant  or  on  the  ground  among  grains 
of  sand. 

At  Highland,  111.,  August  11,  I  found  on  the  red  clover  large  num- 
bers of  both  sexes  of  a  tree-cricket  (CEcanthus),  and  watched  them 
devour  the  clover-aphid  at  a  great  rate.  Afterward  we  kept  these 
tree-crickets  alive  in  the  insectary  for  a  long  time  and  found  it  no 
small  trouble  to  keep  them  supplied  with  enough  plant-lice.  Big,  as 
compared  with  their  victims,  they  soon  cleaned  a  plant  of  aphids.  One 
male  ate  nineteen  full-sized  aphids  at  one  meal,  lasting  fifty-five  min- 
utes, an  aphid  being  finished  in  ten  to  ninety-five  seconds, — about  one 
louse  per  minute  on  an  average.  In  this  instance,  it  should  be  said, 
Mr.  Kelly  facilitated  matters  by  handing  the  cricket  a  new  aphid  as 
soon  as  the  old  one  was  finished.  The  same  cricket,  on  the  following 
day,  being  induced  to  repeat  his  performance,  beat  his  previous  record 


1909] 


THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA 


151 


by  devouring  eleven  aphids  in  eighteen  minutes,  but  fell  short  of  his 
record  for  fifty-five  minutes. 

As  an  inveterate  enemy  of  M.  pisi,  this  (Ecanthus  is  undoubtedly 
far  ahead  of  Dr.  Fletcher's  Diplosis  in  capacity,  but  unfortunately  does 
not  appear  to  be  wide-spread,  tho  it  is  probably 
common  in  southern  Illinois. 

This  species  of  (Ecanthus  agreed  with  none 
of  the  published  descriptions,  but  I  found  that 
Mr.  C.  A.  Hart  and  Mr.  J.  D.  Hood  had  seen  the 
same  species  and  given  it  the  manuscript  name  of 
confluens. 

Triphleps  insidiosus,  an  active  little  flower- 
bug  (Fig.  10)  frequently  impales  M.  pisi  and 
sucks  its  blood.  In  our  breeding  experiments 
with  the  clover-louse  this  little  intruder  had  to  be 
excluded,  as  it  played  mischief  with  the  birth- 
records. 

Podisus  (Fig.  11)  and  Euschistus  (Fig.  12)  as  nymphs  or  adults 
destroy  a  clover-louse  once  in  a  while,  as  I  noticed. 


FIG.  10.— Triphleps  insid- 
iosus. Enlarged.  (Af- 
ter Riley.) 


FIG.  11. — Podisus  maculiventris,  nymph, 
sucking  the  blood  from  a  caterpillar. 
Natural  size. 


FIG.  12. — Euschistus  variolarius.   Four  times 
natural   size. 


The  soldier-beetle  (Podabrus  rugulosus}  was  found  feeding  on  M. 
pisi  in  Maryland,  by  Johnson. 

A  small  red  mite  (Rhyncholophus  pcvrvus)  was  noted  by  Sander- 
son as  feeding  on  M.  pisi  in  Delaware. 

Let  us  now  turn  to  the  parasites  of  Macrosiphum  pisi. 

Aphidius. — Often  there  is  found  on  a  clover  leaf  a  dead  aphid, 
light  brown  in  color,  with  the  body  distended,  attached  to  the  leaf  in  a 
somewhat  lifelike  position  by  means  of  a  little  silken  mat,  which 


152  BULLETIN  No.  134  [April, 

spreads  out  under  the  aphid  and  raises  it  above  the  surface  of  the  leaf. 
(PL  II.,  Fig.  4.)  This  cocoon  was  made  by  a  maggotlike  larva  that 
had  been  feeding  inside  the  body  of  the  aphid.  The  winged  braconid 
emerges  by  cutting  nearly  a  circle  thru  the  skin  of  the  host,  usually 
thru  the  abdomen,  and  leaves  a  circular  opening  with  usually  a  cor- 
responding lid.  The  mother  Aphidius  inserts  a  single  egg  into  the 
body  of  an  aphid. 

Two  species  of  Aphidius  are  named  in  the  literature  as  destroying 
M.  pisi:  A.  Hetcheri  Ashm.  MS.,  reported  by  Fletcher  as  having  done 
good  service  in  Ottawa,  Can.,  and  bred  from  M.  pisi  in  Delaware  by 
Sanderson;  and  A.  washing tonensis  Ashm.,  also  bred  by  Sanderson 
under  the  same  circumstances.  In  Delaware,  at  least  5  percent  of  the 
lice  were  killed  by  these  parasites. 

In  Urbana,  Aphidius  is  abundant  every  season  on  the  clover-louse. 
We  have  had  the  adults  emerge  June  21,  26;  July  1,  3,  4,  6/8,  12,  17; 
August  18,  24;  and  October  18,  19,  — mostly  early  in  July,  however. 

An  Aphidius  larva  that  I  found  July  11  spun  its  oval  silken  carpet 
under  the  aphid  on  the  same  day;  July  12  the  aphid  had  been  raised 
above  the  leaf  and  the  cocoon  was  complete;  July  18  the  adult  was 
found,  it  having  issued  during  the  preceding  twenty-four  hours.  An- 
other black  larva  spun  June  18  and  the  imago  emerged  June  26.  From 
a  cocoon  made  October  12  the  adult  issued  October  19. 

October  10  a  female  Aphidius  was  put  into  a  cage  containing  M. 
pisi,  the  individuals  of  which  had  been  reared  under  glass  in  a  way  to 
insure  their  freedom  from  parasites.  No  oviposition  was  witnessed 
(the  mother  dying  October  21),  but  November  16  three  of  the  aphids 
showed  the  cocoons  of  Aphidius,  the  aphids  having  turned  brown  on 
the  day  before.  These  aphids  were  kept  over  winter  in  glass  vials, 
and  June  10  a  winged  Aphidius  was  found  to  have  emerged.  It  was 
dead  then,  but  certainly  did  not  issue  before  March  17,  when  the  vials 
were  thoroly  examined. 

Another  braconid,  Trioxys  (Praon)  cerasaphis,  was  bred  in  large 
numbers  by  Fletcher  from  material  collected  at  Ottawa,  Canada,  the 
material  referred  to  being  by  implication  M.  pisi. 

From  what  has  been  given  it  can  be  seen  that  a  good  many  differ- 
ent insects  have  to  do  with  Matrosiphum  pisi  in  one  way  or  another, 
and  that  the  interrelations  of  some  of  them  are  involved.  Thus, 
Meqilla  maculata,  which  eats  M.  pisi,  is  parasitized  by  Perilitus  ameri- 
canus,  and  preyed  upon  by  Euschistus  variolarius — the  eggs  of  which 
are  food  for  one  of  the  proctotrypids.  Syrphida  destroy  M.  pisi  and  are 
themselves  food  for  the  same  Euschistus]  furthermore,  they  are  para- 
sitized by  Bassus  latotorius,  which,  in  turn,  is  parasitized  by  Pachyneu- 
ron  syrphi  and  Isocratus  vulgaris. 

Among  the  natural  enemies  of  this  aphid  is  to  be  counted  the 
English  sparrow,  according  to  a  correspondent  of  Dr.  J.  B.  Smith,  who 
wrote,  "It  was  wonderful  to  watch  them,  how  soon  they  cleared  up  a 
pea-vine.  After  the  sparrows  commenced  to  work,  they  soon  cleared 
up  every  louse." 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  153 

Control. — The  treatment  of  the  pest  is  different  according  to 
whether  the  insect  feeds  on  peas  or  on  clover. 

Growers  in  the  eastern  United  States  and  in  Canada  have  found 
that  early  peas  are  practically  exempt  from  injury,  and  therefore  plant 
the  early-maturing  varieties  when  injury  is  probable. 

On  peas  grown  for  commercial  purposes,  spraying  is  too  expen- 
sive, besides  being  in  other  respects  impracticable,  according  to  John- 
son's elaborate  experiments  in  Maryland.  Sanderson  found,  in  Dela- 
ware, some  little  advantage  in  spraying  while  the  lice  are  still  confined 
to  the  terminals  and  the  vines  are  as  yet  upright. 

A  crop  can  be  saved  by  the  timely  and  thoro  use  of  the  "brush  and 
cultivator"  method  devised  by  Johnson.  This  method  requires  that  the 
peas  be  planted  in  rows  24  or  30  inches  apart,  instead  of  being  sown 
broadcast.  The  lice  are  brushed  off  the  vines  with  switches  of  pine 
branches  or  something  similar,  and  are  then  buried  under  ground  by 
means  of  a  cultivator  drawn  by  a  single  horse.  Cultivation  should  not 
be  repeated  for  three  days,  in  order  to  insure  the  death  of  the  buried 
lice.  On  a  hot  day,  Johnson  found  that  lice  left  on  the  surface  of  the 
ground  died  in  a  few  minutes  when  the  temperature  of  the  air  was 
94°-96°  F.,  and  that  of  the  ground  115°- 119°  F.  In  one  instance,  600 
acres  of  peas  were  saved  in  this  way;  and  tho  forty  men  were  neces- 
sary for  two  weeks  to  brush  and  cultivate  the  peas,  the  crop  netted  the 
owner  25,000  to  30,000  cases  of  peas  of  two  dozen  cans  each. 

Instead  of  a  cultivator  a  large  shallow  pan  can  be  used,  and  the 
lice  brushed  into  this  as  it  is  dragged  between  the  rows  by  hand.  In 
such  a  contrivance,  containing  a  little  water  and  kerosene,  Johnson 
collected  a  bushel  of  lice  to  each  row  of  J25  rods.  The  pan,  made  of 
galvanized  iron,  may  be  five  or  six  inches  deep,  and  as  wide  as  the 
distance  between  the  rows.  Sanderson  recommends  this  method  as 
being  perhaps  the  best  one.  It  can  be  used  when  the  soil  is  too  damp 
for  the  cultivator. 

Sanderson  states  that  high  fertilization  (as  with  crimson  clover 
and  lime),  with  frequent  cultivation  for  several  years,  often  enables  a 
crop  of  peas  to  mature  in  spite  of  the  louse. 

As  the  louse  winters  in  the  clover  field  and  spreads  from  clover 
to  peas,  these  should  be  planted  as  far  from  clover  as  possible.  If  the 
lice  are  abundant  on  clover  in  spring  it  may  be  advisable  to  plow  the 
clover  under,  and  roll  the  ground,  in  order  to  save  the  peas  (Sander- 
son). 

In  gardens  the  louse  can  be  controlled  on  green  peas  and  flow- 
ering sweet  peas  by  spraying,  as  with  whale-oil  soap  (1  pound  to  5 
gallons  of  water)  or  kerosene-soap  emulsion,  diluted  with  12  parts  of 
water.  Fletcher  reports  success  with  a  spray  of  whale-oil  soap  and 
tobacco  decoction.  He  put  10  pounds  of  tobacco  leaves  into  half  a 
barrel  of  water,  strained  off  the  liquid  after  a  few  hours,  added  2 
pounds  of  whale-oil  soap,  and,  when  this  was  dissolved,  added  enough 
water  to  make  40  gallons.  Two  days  after  the  application  of  this 
spray  to  both  surfaces  of  the  leaves  most  of  the  lice  were  dead,  and 


154  BULLETIN  No.  134  [April, 

such  parts  of  the  rows  as  had  received  two  applications  were  cleared 
of  the  insects. 

On  red  clover  I  have  seen  this  aphid  multiply  in  spring  until  its 
numbers  threatened  the  life  of  the  plant,  and  then  disappear,  practi- 
cally, thru  natural  agencies ;  this  for  five  successive  seasons.  A  heavy 
rain  did  the  work  assisted  by  the  fungus  Empusa  aphidis  and,  second- 
arily, by  the  numerous  and  important — tho  somewhat  lagging — pre- 
daceous  and  parasitic  insect  foes  of  the  aphid.  _  Were  it  not  for  these 
influences  the  louse  would  become  a  pest  of  the  first  magnitude  in 
spite  of  the  vigor  of  the  clover  plant.  Occasionally  and  locally  it  does 
become  such  a  pest,  as  already  related. 

Unfortunately,  it  can  not  be  predicted  whether  the  clover  will  be 
killed  or  not,  and  if  one  is  unwilling  to  take  the  chances,  the  safest 
thing  to  do  is  to  cut  the  clover  just  as  soon  as  possible.  Cutting  and 
drying  the  clover  will  kill  most  of  the  lice  at  any  time  during  the  sea.- 
son. 

The  hordes  of  lice  are  for  the  most  part  the  progeny  of  the  fewer 
lice  of  May,  in  the  same  field.  So  it  follows  that  spring  pasturing  or 
clipping  back  the  clover  would  check  the  multiplication  of  the.  louse. 

The  lice  of  April  and  May  are  the  progeny  of  a  comparatively 
few  wintered  females  that  entered  the  field  the  preceding  year,  and 
also  of  a  few  eggs  laid  the  previous  autumn  in  the  first-year  clover. 
Therefore  it  is  advisable  to  cut  or  pasture  the  clover  in  the  latter  part 
of  its  first  season — and  this  will  not  hurt  the  plant  if  done  intelligently. 

Macrosiphum  pisi  Kalt. 

1899.  Johnson,  W.  G.— Bull.  No.  20,  N.  S.,  U.  S.  Dept.  Agr., 

Div.  Ent,  pp.  94-99. 

1900.  Johnson,  W.  G.— Can.  Ent.,  Vol.    XXXII.,  pp.  56-60. 
Chittenden,  F.  H.— Bull.  No.  23,  N.  S.,  U.  S.  Dept.  Agr., 

Div.  Ent.,  pp.  33-37. 
Johnson,  W.  G.— Bull.  No.  26,  N.  S.,  U.  S.  Dept.  Agr., 

Div.  Ent.,  pp.  55-59. 
Sanderson,  E.  D.— Bull.  No.  26,  N.  S.,  U.  S.  Dept.  Agr., 

Div.  Ent.,  pp.  69-72. 
Sanderson,  E.  D. — Bull.  No.  49,  Del.  Agr.  Exper.  Sta.,  pp. 

14-24. 
Fletcher,  James. — Rep.  Exper.  Farms  Canada,   1899,  pp. 

170-174. 

1901.  Sanderson,  E.  D.— Can.  Ent.,  Vol.  XXXIII.,  pp.  31-39. 
Sanderson,  E.  D. — Twelfth  Rep.  Del.  Agr.  Exper.   Sta., 

1900,  pp.  169-186. 

Fletcher,  James. — Rep.  Exper.  Farms  Canada,   1900,  pp. 

211-213. 
Chittenden,  F.  H.— Circ.  No.  43,  U.  S.  Dept.  Agr.,  Div. 

Ent.,  pp.  1-8. 

1902.  Sanderson,  E.  D.— Thirteenth  Rep.  Del.  Agr.  Exper.  Sta.. 

1901,  pp.  168-172. 


1909]  THE  INSECT  PKSTS  OF  CLOVKR  AND  ALFALFA  155 

CLOVER  LEAF-WEEVIL 
Phytonomus  punctatus  Fab. 

Tho  this  insect  must  be  counted  among  the  most  important  clover 
pests,  it  has  not  as  yet  established  itself  as  an  annual  menace  to  the 
hay  crop.  Indeed,  it  is  ordinarily  held  in  check  by  a  great  variety  of 
adverse  influences,  and  seldom  gets  control  of  the  plant — reminding 
one,  in  this  respect,  of  the  army-worm. 

In  early  spring  the  larvae  make  small  round  holes  in  the  leaves  of 
second-year  clover,  as  soon  as  the  leaves  have  begun  to  grow ;  later, 
they  eat  inward  from  the  margin,  the  injury  increasing  in  April  and 
May.  Thruout  the  summer  the  beetles  gnaw  the  clover  leaves  in  a 
ragged  fashion  and  may  even  eat  the  plant  down  to  the  roots. 

The  larvae  and  beetles  are  not  seen  in  the  daytime,  unless  one 
hunts  for  them ;  they  are  nocturnal  in  their  activity.  The  larvae,  curled 
up  under  rubbish  on  the  ground,  are  green  with  a  white  stripe  along 
the  middle  of  the  back ;  they  have  no  legs  and  are  sluglike  when  in- 
active. The  adults — tough,  oval,  brown  beetles — are  also  found  on 
the  ground  during  the  day,  motionless,  with  the  legs  and  antennae 
drawn  up  against  the  body,  or  else  moving  away  sluggishly  when  ex- 
posed to  the  light. 

Distribution. — Tho  this  species  has  been  familiar  to  European  en- 
tomologists for  more  than  a  century,  occurring  as  it  does  thruout 
Europe  and  in  western  Siberia,  it  was  not  recognized  in  this  country 
until  1881,  when  its  ruinous  work  was  reported  from  Yates  county, 
New  York.  At  present  the  species  is  known  to  occur  in  Vermont, 
Rhode  Island,  Connecticut,  New  York,  New  Jersey,  Pennsylvania, 
Delaware,  Maryland,  District  of  Columbia,  West  Virginia,  North  Car- 
olina, Ohio,  Indiana,  Illinois,  Michigan,  and  Wisconsin,  and  also  in 
Ontario,  Canada.  From  the  data  collected  by  F.  M.  Webster,  the  in- 
sect appears  to  have  spread  from  New  York  into  Ohio,  then  westward ; 
also  from  New  York  into  Canada.  At  Ridgeway,  Ont.,  Mr.  A.  H. 
Kilman  found  that  the  beetles  were  being  brought  by  the  east  wind, 
August  10,  1884.  On  the  same  day,  at  Buffalo,  N.  Y.,  ten  miles  due 
east  of  Ridgeway  and  across  the  lake,  the  beetles  swarmed  on  the 
pavements  and  could  be  collected  by  the  quart  along  the  lake  shore. 
Reinecke  noted  their  abundance  in  Buffalo  following  a  heavy  east 
wind. 

Food  Plants  and  Injuries. — The  food  plants  in  Europe  are  given  as 
Tri folium  (clover)  and  Medicago  sativa  (lucerne,  alfalfa).  In  the 
United  States  the  insect  eats  all  kinds  of  clovers,  and  alfalfa  as  well. 
The  other  food  plants  that  have  been  named,  are  beans  and  timothy  for 
the  larva,  and  burdock  and  the  flowers  of  goldenrod  for  the  beetle. 

Webster  observed  a  preference  for  white  clover  over  red.  In 
central  Illinois  red  clover  is  most -heavily  infested,  alfalfa  coming  sec- 
ond, and  white  clover  third.  Mammoth  clover  and  alsike  are  freely 
eaten  if  they  happen  to  be  available. 

European  accounts  refer  but  scantily  to  this  species  as  a  pest, 
aside  from  references  to  its  devastations  in  Italy  in  the  years  1867-70; 


156 


BULLETIN  No.  134 


[April, 


and  in  this  country  the  insect,  tho  often  abundant,  seldom  accomplishes 
the  injury  anticipated  because  the  larvae  are  usually  killed  in  spring  by 
a  fungous  disease.  When  this  species  cooperates  with  the  root-borer, 
in  a  time  of  drought,  injury  of  the  worst  kind  may  ensue. 

The  larvae  eat  the  leaves,  and  the  beetles  eat  the  leaves  and  stems 
also,  as  described  later. 

Description. — The  egg  is  easily  visible  as  a  yellow  object  (chrome- 
yellow  at  first),  elongate  oval,  1.1  mm.  long  and  0.6  mm.  broad.  It 
darkens  in  from  two  to  six  days  after  being  laid,  and  the  surface  is 
then  rough,  and  sculptured  with  hexagonal  depressions. 

In  the  clover  field  the  larvae  of  this  species  (Fig.  13)  can  not  easily 
be  mistaken  for  anything  else.  They  are  green  usually,  and  lie  on  the 
ground  curled  head  to  tail.  Close  examination  shows  that  they  are 

footless  and  have  a  brown  head,  while  along 
the  middle  of  the  back  is  a  white  or  pale 
yellow  stripe  edged  with  rose-red  or  black- 


FIG.  14. —  Clover  leaf-weevil,  Phytono- 
mus  punctatus,  cocoon.  Greatly  en- 
larged. 


ish  red.     The  youngest  larvae,  to  be  sure, 
FIG.  13.—  Clover  leaf-weevil,      differ  f rom  this  description,  for  when  only 

Phytonomus  punctatus,  lar-         i    c  -7  Inno-     fli^v    HT-A    virhirp    r>r 

va.    Greatly  enlarged.  1'3   mm-   or  Z   mm-    long>   tney   are    WHltC   < 

pale  yellow,  with  a  jet-black  head  and  only 

a  suggestion  of  the  characteristic  median  dorsal  stripe ;  they  are  curled 
up  on  the  ground  and  sluggish,  however,  just  like  the  older  larvae. 

Riley  (1882,  p.  178)  gave  a  detailed  description  of  the  larva  in  its 
four  stages.  The  body  tapers  gradually  toward  each  end.  The  color, 
white  at  hatching,  becomes  green  as  soon  as  a  meal  has  been  taken. 
Some  larvae,  however,  are  distinctly  yellow  instead  of  green,  and  a 
few  are  bluish  green.  The  head,  black  in  the  first  stage,  becomes 
afterward  brown  or  yellowish  brown.  The  second  stage  (after  the 
first  moult)  is  marked  by  the  appearance  of  the  broad  white  dorsal 
line,  bordered  on  each  side  by  a  blackish  streak,  and  the  length  of  the 
larva  is  4  mm.  After  the  second  moult  this  line  is  more  conspicuous 
and  the  length  of  the  larva  is  5  to  7  mm.  With  the  third  and  final 
moult,  the  larvae  become  decidedly  green,  tho  the  posterior  part  of  the 


1909] 


THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA 


157 


body  remains  yellowish;  the  dorsal  line  becomes  tinged  with  rose 
color  and  edged  with  blackish  rose;  length  8  to  14  mm.  The  cocoon 
is  oval  (Fig.  14),  9-10  mm.  long  and  6.5-7  mm.  broad,  and  is  com- 
posed of  a  coarse  network  of  brownish  threads. 

The  newly  formed  pupa  (Fig.  15)  has  a  yellowish  green  head, 
small  black  eyes,  and  yellow  antennae,  legs,  and  wing-pads.  The  abdo- 
men is  dark  green  with  a  pale  dorsal  line,  and  bears  numerous  hairs  at 
its  extremity  and  a  transverse  series  of  dorsal  setae  on  each  of  its  seg- 
ments. 

The  beetle  (Fig.  16)  is  a  stout,  oval,  brown,  finely  punctured  cur- 
culio.  The  female  is  about  8  mm.  in  length  and  4.5  mm.  in  greatest 
width,  some  specimens  being  as  long  as  8.5  mm.  The  prevailing  color 


FIG.  15. 


FIG.  16. 


Clover  Leaf-weevil,  Phytonomus  pwnctatus:    Fig.    15,  pupa;    Fig.    16,  beetle. 
Greatly  enlarged. 

above  is  brown,  but  the  sides  of  the  prothorax  and  elytra  are  washed 
with  pale  yellowish  brown,  which  on  the  elytra  covers  the  outer  five 
interspaces.  Occasionally  there  is  a  pale  sutural  line.  The  elytra  are 
marked  above  with  small  black  spots,  due  to  scales  which  occur  at  regu- 
lar intervals  on  the  interspaces.  The  prothorax  is  much  narrower  than 
the  abdomen,  subquadrate,  and  one  fifth  broader  than  long,  with  the 
sides  rounding  anteriorly  and  converging  slightly  posteriorly.  The 
pronotum  has  three  pale  longitudinal  lines,  one  in  the  middle  and  one 
on  each  side.  The  eyes  are  transverse.  The  beak  is  half  as  long 
again  as  the  head,  stout  and  curved,  with  deep  antennal  grooves.  The 
scales  and  the  short  sparse  setae  of  the  body  are  either  brown  or  yel- 
iow. 

The  male,  7  mm.  in  maximum  length,  differs  from  the  female  in 
being  smaller  and  narrower,  with  the  sides  of  the  elytra  less  rounded; 


158  BULLETIN  No.  134  [April, 

it  is  also  darker  in  color  than  the  female,  with  a  narrower  pale  area  on 
each  elytron,  the  two  outermost  interspaces  being  dark  instead  of  pale. 
The  pygidium  (which  is  not  exposed)  is,  as  usual  in  the  family  Cur- 
culionidce,  divided  by  a  transverse  suture  so  as  to  form  an  additional, 
or  anal,  segment;  thus  the  male  has  eight  "dorsal  segments"  and  the 
•  female  seven. 

P.  punctatus  is  distinguishable  at  once  from  our  other  species  of 
Phytonomus  by  its  coloration,  large  size,  and  stout  beak.  As  to  smaller 
differences,  punctatus  is  characterized  by  having  mandibles  that  are  not 
emarginate  at  the  tip,  while  the  first  and  second  segments  of  the  funicle 
are  equal ;  in  the  other  species  of  the  genus  the  first  segment  is  stouter 
and  often  longer  than  the  second,  and  the  beak  is  longer  and  more 
slender  than  in  punctatus.  In  the  clover  field,  this  beetle  will  be  recog- 
nized without  difficulty. 

Life  History. — In  central  Illinois  we  have  only  one  annual  gener- 
ation of  this  insect,  as  seems  to  be  the  rule  elsewhere.  All  thru  the 
winter  small  larvae  can  be  found  in  the  clover  field  under  rubbrsh  on 
the  ground  or  between  the  bases  of  the  clover  stems.  In  early  spring 
the  few  warm  days  that  start  the  clover  on  its  new  growth  revive  the 
larvae  also,  and  they  begin  to  mar  the  fresh  clover  leaves  with  little 
round  holes  eaten  out  of  the  blades  of  the  leaflets.  In  the  early  season 
of  1907  the  first  new  leaves  of  red  clover  began  to  show  March  19,  and 
were  already  riddled  by  these  larvae  March  23,  at  which  date  the  larvae 
were  common  on  the  ground  near  the  affected  plants.  In  early  spring 
the  larvae  are  of  many  sizes,  with  an  average  of  5  mm.  in  length,  tho 
many  are  only  2  or  2.5  mm.  long,  and  a  few  are  as  long  as  7  mm.  I 
have  rarely  found  the  beetles  in  early  spring,  and  such  as  were  found 
were  either  dead  or  in  the  last  stages  of  decrepitude,  and  evidently  in- 
capable of  doing  anything  toward  the  propagation  of  their  kind. 

I  have  not  found  more  than  four  larval  stages — the  number  given 
by  Riley.  The  first  stage  lasts  about  nine  days,  in  the  insectary ;  thus 
larvae  born  November  16  moulted  for  the  first  time  November  25. 
Some  of  the  larvae,  born  in  late  autumn,  do  not  moult  until  the  following 
March  or  April.  For  example,  one  larva  was  in  its  first  stage  April 
1 ;  it  moulted  April  8,  April  17,  and  May  4,  and  spun  May  20.  The  in- 
tervals between  moults  are,  however,  very  variable,  especially  when  the 
weather  is  unsettled,  and  the  growth  of  the  larvae  is  consequently  in- 
termittent. 

The  pupal  period  indoors  we  have  found  to  be  10  to  20  days,  as 
in  four  instances  following: 

( 1 )  Spinning  occurred  April  22 ;  pupation,  April  24 ;  emergence, May  1 1 . 

(2)  Spinning  occurred  April  22 ;  pupation,  April  24 ;  emergence,  May  14. 

(3)  Spinning  occurred  April  24 ;  pupation,  April  30 ;  emergence,May  20. 

(4)  Spinning  occurred  May  20 ;  pupation,  May  27  ;  emergence,  June    6. 

Larvae  of  various  sizes  are  common  in  April  and  May,  but  nearly 
all  attain  their  growth  before  June  20.  Rarely,  beetles  of  the  new  gen- 
eration appear  as  early  as  May  9;  on  that  date  we  once  found  two 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  159 

freshly  emerged  beetles  in  the  field.  The  latest  date  for  their  emer- 
gence may  be  given  as  July  15.  Many  beetles  issue  daily  from  June 
5  to  June  30,  and  most  of  the  beetles  issue  during  the  last  week  of 
June. 

Early  as  the  beetles  appear,  they  do  not  begin  to  mate  until  the  last 
week  of  August,  and  nearly  air  the  eggs  are  laid  in  September  and 
October. 

We  have  insectary  records  of  oviposition  for  almost  every  day  be- 
tween September  17  and  October  26,  and  almost  daily  records  of 
hatching  from  October  9  to  November  27.  The  egg  period  in  autumn 
is  from  23  to  45  days,  averaging  29  days ;  the  length  of  the  period  de- 
pends upon  temperature  chiefly;  some  of  the  latest  eggs,  indeed, 
do  not  hatch  until  the  following  spring.  Out-of-doors  we  have  found 
eggs  as  late  as  November  14,  and  young  larvae  as  early  as  October  10. 
After  that  date  they  soon  become  common,  and  can  be  found  at  any 
time  during  the  winter  between  the  bases  of  the  clover  stems,  as  deep 
as  possible,  or  else  on  the  ground  under  more  or  less  protection.  Many 
of  them  succumb  to  the  cold,  however.  These  winter  larvae  also  are 
of  various  sizes.  Sixty-five  larvae  measured  November  26  ranged  in 
length  from  2.5  mm.  to  7.5  mm.,  with  an  average  of  3.17  mm. 

Late  in  October  a  few  living  beetles — more  than  three  months  old 
— occur  in  the  clover  field  and  go  into  hibernation.  Early  in  the  fol- 
lowing spring  their  dead  bodies  may  be  found.  Farther  south,  it  is 
possible  that  enough  beetles  survive  the  winter  to  influence  the  course 
of  the  life  history. 

The  preceding  general  account  of  the  life  history  is  based  upon 
such  a  large  body  of  observations  that  it  represents  the  actual  condi- 
tions with  considerable  accuracy,  for  central  Illinois.  A  few  precise 
notes  are  added  on  account  of  their  significance. 

Many  eggs  laid  between  October  16  and  25,  1905,  were  apparently 
sound  January  21,  1906,  and  had  not  hatched  February  23;  but 
March  21,  young  larvae  from  them  were  found,  still  alive,  and  2  mm.  in 
length.  Again,  eggs  laid  October  26,  1904,  did  not  hatch  until  April 
13,  1905. 

I  have  several  times  followed  the  consecutive  life  history  for  a 
year  or  more.  The  longest  account,  covering  a  period  of  eighteen 
months,  begins  with  a  female  beetle  taken  September  23,  1904.  She 
laid  eggs  as  follows: 

Sept.  26,  one  mass  of  eggs. 

Oct.  1,  three  egg-masses;  hatched  Nov.  3  and  4;  larvae  alive  Nov. 
21,  but  died  during  winter. 

Oct.  9,  several  eggs  laid ;  they  hatched  November  19 ;  the  larvae 
died  in  winter. 

Oct.  26,  several  eggs  laid ;  unhatched  April  12,  1905 ;  hatched 
April  13. 

Nov.  1,  three  eggs;  hatched  Nov.  27,  in  warm  room.  The  mother 
was  alive  Nov.  21,  but  died  during  the  winter. 

The  larvae  that  were  born  April  13,  1905,  were  reared;  they  buried 


160  BULLETIN  No.  134  [April, 

themselves  in  the  ground  May  23  and  24  and  gave  beetles  June  13. 
Four  of  these  beetles  were  kept  alive  until  August  28,  and  August  29 
one  male  and  one  female  remained.  The  female  laid  eggs  Oct.  16,  17, 
21,  24,  and  25.  These  eggs  had  not  hatched  February  23,  1906,  but 
had  just  hatched  March  21 ;  by  March  29  the  larvae  had  died,  however, 
from  a  scarcely  excusable  neglect  to  supply  them  with  food.  The' 
parent  beetles  had  died  the  year  before,  about  November  11. 

This  account  of  the  life  history  is  in  some  respects  at  variance 
with  that  of  Riley  (1882,  pp.  175,  176).  In  central  Illinois  the  egg 
period  in  autumn  is  from  23  to  45  days  in  the  breeding-cage.  Fur- 
thermore, none  of  the  larvae  born  in  autumn  give  beetles  in  that  season ; 
the  beetles  do  not  emerge  until  the  following  June  or  thereabouts,  and 
some  of  these  are  the  beetles  that  will  enter  upon  hibernation.  In  my 
experience,  no  eggs  are  laid  in  spring.  In  a  warmer  latitude  than  this 
there  might  very  well  be  a  second  generation  of  beetles,  to  hibernate 
and  to  lay  eggs  the  following  spring.  Indeed,  in  this  latitude,  the  little 
autumn  larvae,  if  taken  indoors  and  fed,  will  produce  beetles  in  mid- 
winter. 

Here,  then,  the  clover  leaf-weevil  winters  chiefly  as  a  small  larva ; 
occasionally  in  the  egg;  never  as  a  pupa,  in  my  experience;  and  rarely 
as  a  beetle.  No  eggs  are  laid  in  spring,  however,  and  there  is  clearly 
but  one  generation  a  year,  tho  this  generation  is  straggling  instead  of 
compact. 

Habits. — The  larvae  that  have  hibernated  are  ready  to  eat  the  red 
clover  as  soon  as  it  starts  on  its  second  year's  growth.  At  any  time 
during  the  winter  one  can  get  plenty  of  these  larvae  by  digging  up 
clover  sod  and  starting  the  growth  of  the  clover  indoors. 

In  midwinter,  on  a  mild  day  (Jan.  6,  1903),  the  larvae  were  feeding 
in  abundance  on  red  clover  plants  in  Urbana,  111.  (R.  D.  Glasgow)— 
and  in  broad  daylight.  This  is  unusual,  for  at  other  times  of  the  year 
they  feed  only  at  night  or  else  -at  dusk  or  in  daytime  when  the  sky  is 
sufficiently  cloudy.  Ordinarily,  when  the  sun  is  shining  they  are  found 
curled  up  in  shaded  situations,  usually  on  the  ground,  but  occasionally 
.among  the  stems  of  their  food  plant.  When  feeding  at  night  the  larger 
larvae  drop  to  the  ground  when  approached,  but  the  smaller  ones  re- 
main clinging  to  the  leaflets,  just  as  Riley  observed.  The  larva  fre- 
quently curls  itself  around  the  edge  of  a  leaflet  and  bites  out  a  small 
round  piece  from  the  blade ;  or  it  may  secure  a  hold  by  gripping  a  hair 
of  the  leaf  between  two  of  its  body  segments.  Only  the  youngest  larvae 
make  the  little  round  holes  in  the  leaflets ;  the  older  larvae  eat  gaps  in 
the  edges. 

The  feeding  of  the  larvae  in  spring  is  more  or  less  intermittent, 
being  suspended  at  every  cold  spell.  In  1907,  when  the  entire  month 
of  April  was  cold  in  central  Illinois  and  frequent  freezes  blackened 
more  than  one  third  of  the  red  clover  leaves,  the  larvae  of  the  leaf- 
weevil,  like  their  food  plant,  made  no  growth  during  the  month  of 
April,  but  became  dormant  again  until  May,  tho  they  had  been  active 
during  the  warm  weather  of  late  March.  Retarded  in  their  develop- 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  161 

ment  by  one  month,  they  made  up  in  May  for  what  they  had  lost,  and 
the  majority  of  the  beetles  appeared  at  the  usual  time  in  June. 

The  locomotion  of  the  larva  is  peculiar.  The  larva  secures  a  hold 
on  a  hair  by  means  of  its  mouth ;  then  brings  forward  the  end  of  the 
abdomen  to  secure  a  new  hold,  and  stretches  forward  the  rest  of  the 
body.  Tho  the  larva  is  termed  footless,  it  has,  nevertheless,  paired 
ventral  fleshy  tubercles  which,  from  their  anatomical  relations,  are  evi- 
dently equivalent  to  the  legs  of  other  larvae ;  also  a  median  ventral  pro- 
thoracic  tubercle.  These  muscular  tubercles  assist  in  locomotion, 
especially  on  smooth  surfaces.  As  the  larva  walks  on  the  under  side 
of  a  sheet  of  glass,  slightly  moistened,  a  suckerlike  action  of  these 
tubercles  is  evident. 

The  color  of  the  larva  is  white  at  birth,  but  a  green  tinge  appears 
as  soon  as  the  larva  has  taken  its  first  meal  of  green  plant  tissue. 
Some  larvae  are  yellow  instead  of  green ;  diseased  larvae  are  generally 
yellow,  tho  not  all  yellow  larvae  are  diseased.  Now  and  then  a  larva  is 
found  having  a  decided  blue  tinge. 

When  full  grown  the  larva  buries  itself  just  under  the  surface  of 
the  soil  and  makes  an  oval  cell,  against  the  smooth  wall  of  which  it 
spins  the  cocoon;  once  in  a  while  the  cocoon  is  constructed  among  the 
bases  of  green  clover  stems.  The  cocoon,  oval  in  form,  consists  of  a 
coarse  network  of  threads  with  round  or  oval  meshes ;  it  is  pale  yellow 
at  first,  becoming  brownish  with  age.  The  actual  spinning  is  done 
with  the  mouth.  The  first  threads  are  laid  in  haphazard  fashion  across 
one  another;  but  after  a  coarse  framework  has  been  made,  the  larva 
lays  the  later  threads  along  beside  the  earlier  ones,  forming  a  stout 
network,  and  gradually  reducing  the  meshes  to  small  rounded  holes. 
At  intervals  the  supply  of  silk  fluid  in  the  mouth  gives  out;  then  the 
larva  reaches  back  to  the  end  of  the  abdomen  and  by  an  assiduous 
process  of  nibbling  secures  a  new  supply  of  the  silk  fluid  from  the  rec- 
tum, and  resumes  its  spinning.  This  performance  always  occurs,  and 
can  be  observed  easily  with  a  hand  lens  in  the  earlier  stages  of  cocoon- 
spinning.  Riley  and  J.  A.  Osborne  were  each  partly  correct  in  their 
accounts  of  the  spinning  (Riley,  1882,  p.  175). 

The  beetle  eats  its  way  out  of  the  cocoon  and  enters  upon  a  long 
and  lazy  existence  of  feeding  by  night  and  resting  by  day.  Not  until 
the  last  of  August  do  the  beetles  arouse  to  reproductive  activity.  In 
summer  they -are  sluggish  in  the  daytime,  under  debris  on  the  ground, 
but  at  night'they  are  contrastingly  alert.  They  reduce  clover  leaves  to 
rags,  beginning  at  the  margins  and  eating  inward,  usually  leaving  the 
stout  bases  of  the  veins,  but  sometimes  devouring  the  entire  plant  down 
to  the  ground — stalks,  flower  heads,  and  all.  Incidentally,  they  spot 
the  plants  with  a  brown  fluid.  Like  the  larvae,  they  are  quick  to  drop 
when  approached. 

We  have  many  times  kept  these  beetles  alive  all  summer,  waiting 
for  them  to  lay  eggs.  When  the  time  comes  they  lay  the  conspicuous 
yellow  eggs  in  profusion  in  the  breeding-cages,  with  or  without  method, 
as  the  case  may  be.  The  female  may  scatter  her  eggs  about  promis- 


162  BULLETIN  No.  134  [April, 

cuously  or  place  them  in  small  bunches  on  the  plant  or  elsewhere.  In 
other  instances  she  bites  a  hole  in  a  clover  stem  and  inserts  an  egg 
lengthwise,  pushing  it  far  in  or  leaving  it  sticking  out  of  the  stem. 
Sometimes  she  makes  a  cavity  without  laying  an  egg  in  it.  Often  the 
female  eats  her  eggs.  In  a  breeding-cage  that  is  sufficiently  shaded, 
eggs  may  be  laid  during  the  day ;  normally  they  are  laid  at  night.  Mr. 
R.  L.  Webster  observed  oviposition  in  our  insectary  October  16,  begin- 
ning at  6 :30  p.  m.  He  found  a  female  clinging  to  a  clover  stem,  with 
her  head  downward,  and  piercing  the  stem  with  her  rostrum,  thrusting 
it  in  almost  to  the  antennae.  At  times  she  would  raise  the  body  on  the 
front  pair  of  legs  as  if  throwing  her  entire  weight  on  the  beak.  Having 
made  a  sufficiently  large  hole,  she  reversed  her  position  and  inserted  a 
single  egg;  the  actual  oviposition  took  not  more  than  twenty  seconds. 
Then  she  made  another  hole  but  did  not  attempt  to  lay  an  egg  in  it. 

Out-of-doors  the  eggs  are  found  inserted  into  clover  stems,  but 
occur  also,  to  some  extent,  on  the  base  of  the  plant,  where  the  stems 
join;  rarely  they  are  found  on  the  ground. 

The  male  often  accompanies  the  female  on  her  round  of  oviposi- 
tion and  there  are  repetitions  of  the  process  of  fertilization,  alternating 
with  the  periods  of  oviposition.  September  25,  a  pair  of  beetles  were 
put  on  potted  red  clover ;  Sept.  27,  twelve  eggs  were  laid ;  Sept.  28, 
six;  Sept.  29,  several;  Oct.  5,  several;  Oct.  8,  several  more;  Oct.  17, 
copulation  occurred,  probably,  for  the  second  time ;  Oct.  23,  more  eggs 
were  laid ;  Oct.  31,  the  female  was  missing. 

The  largest  number  of  eggs  that  we  have  obtained  from  one 
female  is  forty. 

Usually  the  female  takes  three  or  four  weeks  to  lay  all  her  eggs, 
under  insectary  conditions.  In  the  field  the  period  of  egg-laying  ap- 
pears to  be  shortened,  in  the  last  of  the  season,  by  frost. 

Our  observations  on  the  habits  of  this  species  are  in  accord  with 
those  of  Riley,  except  as  regards  some  minor  details  of  locomotion  and 
silk-spinning. 

Natural  Enemies. — Riley  notes  the  larva  of  a  small  beetle,  Col- 
lops  quadrimaculatus,  as  feeding  upon  the  eggs  of  the  clover  leaf- 
weevil,  and  Cicindela  repanda  as  probably  preying  upon  the  larva  of 
the  weevil.  In  Europe  various  ichneumons  parasitize  Phytonomus 
larvae,  but  in  this  country  no  such  parasites  have  come  to  light  as  yet. 

Webster  mentions  the  fact  that  the  larvae  are  destroyed  by  birds, 
and  that  barnyard  fowls,  especially  turkeys,  are  very  fond  of  them. 

The  worst  enemy  of  the  leaf-weevil  is  an  epidemic  disease,  that 
under  favorable  conditions  sweeps  off  the  larvae  by  the  wholesale. 
This  disease,  due  to  a  fungus,  needs  damp  and  not  too  cold  weather 
for  its  development,  and  affects  the  larvae  in  April  or  May  and  again 
in  October  and  November,  but  not  during  winter.  The  contagion  is 
rapid  and  thoro;  no  matter  how  abundant  the  larvae  are,  the  infection 
spreads  until,  after  two  to  four  weeks,  it  is  almost  impossible  to  find  a 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  163 

living  specimen.  "The  sick  larvae  of  all  ages  crawl  up  the  herbage 
during  the  night,  and  instead  of  again  concealing  themselves  near  the 
ground  on  the  approach  of  light,  as  the  healthy  ones'  do,  ascend  as  high 
as  possible,  and  if  on  grass,  coil  themselves  in  a  horizontal  position 
about  the  apex  of  the  blade,  or  if  on  other  objects,  take  a  position  as 
nearly  similar  as  the  shape  of  the  object  permits.  If  disturbed  before 
the  middle  of  the  forenoon,  the  majority  are  still  able  to  crawl,  although 
sluggishly;  by  noon  most  of  them  are  quite  dead,  but  unchanged  in 
appearance.  It  will  be  found  that  they  cling  to  the  leaf  with  greater 

tenacity  than  during  life Late  in  the  afternoon,  the  body  has 

changed  from  the  normal  yellowish  or  pea-green  and  smooth  appear- 
ance to  a  velvety  gray.  The  next  morning  there  is  only  a  small,  black- 
ened and  shriveled  mass  remaining,  while  the  surrounding  foliage  is 
powdered  with  a  whitish,  clinging  dust,  composed  of  the  spores  of  the 
fungus.  If  some  of  the  dead  insects  had  been  placed  on  a  pane  of 
glass,  and  a  tumbler  inverted  over  them  during  the  night,  they  would 
have  shrunken  less,  and  been  covered  with  a  white  fleecy  growth,  while 
on  the  glass,  surrounding  each  body,  would  have  been  a  white  halo  of 
spores  two-thirds  of  an  inch  in  diameter,  such  as  everyone  has  ob- 
served about  dead  flies  on  the  window  in  autumn.  This  is  the  general 
course  of  this  rapid  and  fatal  disease."  (J.  C.  Arthur.) 

This  fungus,  known  as  Empusa  (Entomophthora)  sphcerosperma 
Fres.,  is  found  in  the  body  of  the  larva  as  a  network  of  colorless 
branching  threads  (mycelium)  which  absorb  the  fluids  of  the  body; 
some  of  the  branches  push  thru  the  ventral  wall  of  the  body  and  attach 
themselves  to  the  nearest  surface  as  holdfasts  (rhizoids)  ;  other 
branches  pierce  the  skin  and  form  a  gray  velvety  coating  on  the  body 
of  the  larva,  and  the  tips  of  some  of  these  branches  each  form  a  spore 
(conidium),  which  is  .finally  projected  forcibly  into  the  air,  to  infect 
any  other  larva 'that  it  may  happen  to  hit.  These  temporary  spores 
germinate  at  once,  pushing  out  one  or  more  threads,  which  enter  the 
host  and  grow,  forming  a  mycelium.  There  are  also  resting  spores ; 
these  develop  within  the  body  of  the  host  and  are  capable  of  surviving 
for  a  longer  period  than  the  temporary  spores. 

Other  and  more  technical  details  in  regard  to  the  fungus  are  given 
by  J.  C.  Arthur  (Fourth  Rep.  N.  Y.  Agr.  Exper.  Sta.,  1885  [1886],  pp. 
258-262)  and  by  Thaxter  (Mem.  Boston  Soc.  Nat.  Hist.,  Vol.  IV., 
1888,  pp.  172-175). 

This  fungus  is  by  no  means  dependent  upon  the  clover  leaf-weevil 
for  its  existence,  for  it  has  a  long  list  of  hosts,  representing  most  of  the 
larger  orders  of  insects.  The  list  includes  the  common  cabbage-worm, 
mosquitoes  and  some  other  flies,  ichneumons,  certain  leaf-hoppers,  etc. 
Fortunately,  also,  the  fungus  is  widely  distributed  in  America  as  well 
as  in  Europe.  In  this  country  the  ravages  of  the  fungus  on  the  leaf- 
weevil  have  been  reported  from  nearly  every  region  in  which  the 
weevil  has  been  injurious. 


164  BULLETIN  No.  134  [April, 

Control. — The  reported  outbreaks  of  the  larvae  in  spring  have  al- 
most always  been  suppressed  by  the  virulent  disease  just  described. 
This  disease  prevents  the  summer  damage  by  the  beetles,  often  killing 
the  larvae  before  they  have  done  much  injury. 

Riley's  recommendation  to  plow  badly  infested  clover  under  in 
May  rather  than  to  allow  it  to  become  a  source  of  contagion,  has  sel- 
dom been  followed  unless  the  clover  root-borer  also  has  been  present, 
for  the  leaf-weevil  by  itself  has  not  often  done  an  immense  amount  of 
damage. 

The  fact  that  the  young  larvae  hibernate,  led  Riley  to  mention  the 
possibility  of  crushing  them  or  burning  them,  but  he  added  his  doubt 
as  to  the  practicability  of  killing  them  by  rolling  or  by  burning  the 
clover  stubble  in  winter.  » 

The  necessity  for  the  employment  of  any  remedy  does  not  appear 
until  the  clover  is  well  on  in  its  second  year's  growth.  If  damage  is  an- 
ticipated, however,  it  would  seem  advisable  to  pasture  the  clover  lightly 
or  to  clip  it  back  in  spring ;  this  does  not  hurt  the  clover,  is  highly  de- 
sirable as  a  means  of  forestalling  the  attacks  of  some  other  clover 
pests,  and  might  check  the  larvae  of  the  leaf-weevil  somewhat,  tho  it 
is  possible  that  they  would  subsist  on  the  cut  stems  until  the  new 
growth  started;  and  in  cold  weather  they  can  live  a  long  time  without 
any  food. 

After  the  second  season  red  clover  should  be  plowed  under  to  get 
rid  of  this  and  other  pests,  as  well  as  for  agricultural  reasons. 

Phytonomus  punctatus  Fab. 

1882.     Riley,  C.  V.— Rep.  [U.  S.]  Comm.  Agr.,  1881-82,  pp.  171- 

179. 

Lintner,  J.  A.— First  Rep.  Ins.  N.  Y.,  pp.  247-253. 
1884.     Kilman,  A.  H.— Can.  Ent.,  Vol.  XVI.,  pp.  144,  145. 
1896.     Webster,  F.  M.— Bull.  No.  68,  Ohio  Agr.  Exper.  Sta.,  pp. 
27-31. 


CLOVER  ROOT-BORER 

Hylastinus  obscurus  Marsh. 

(Hylastes  obscurus,  H.  trifolii  Mull.,  Hylesinus  trifolii  Mull.) 

This  pernicious  root-borer  is  gradually  spreading  over  the  United 
Slates  and  Canada,  and  has  already  ruined  crops  of  clover  in  New 
York,  Ohio,  Indiana,  and  Michigan.  Often  the  injury  done  by  this 
insidious  insect  has  been  attributed  to  drought  or  disease.  The  in- 
jury appears  in  the  wilting  and  death  of  the  plant.  A  badly  injured 
plant  breaks  off  easily,  at  the  crown ;  the  roots  are  burrowed  out  length- 
wise, and  in  the  burrows  can  be  found  white  footless  grubs,  or  little, 
dark  brown,  cylindrical  beetles,  as  tough  in  body  as  the  others  of  their 
family,  Scolytidce. 


1909] 


THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA 


165 


Distribution. — This  beetle  was  introduced  from  Europe,  where  it 
has  been  known  for  more  than  a  century,  feeding  chiefly  on  red  clover 
"but  also  on  alsike.  In  this  country  it  first  attract- 
ed attention  as  a  pest  in  1878  in  central  New 
York.  Thence  it  spread  westward  in  the  region 
of  Lake  Erie,  doing  great  damage  in  Ontario, 
Can.,  in  1888,  appearing  in  Michigan  in  1889  at 
the  west  end  of  Lake  Erie,  and  after  that  spread- 
ing over  southern  Michigan  with  disastrous  con- 
sequences. In  Ohio  it  was  injurious  by  1890, 
and  seriously  so  in  the  northwestern  part  of  the 
state  in  1893.  It  has  reached  Indiana,  Illinois, 
Pennsylvania,  West  Virginia,  and  North  Caro- 
lina, and  has  even  been  reported  from  Oregon. 

.Food  Plants  and  Injury. — In  America  the 
chief  food  plants  are  red  clover  and  mammoth 
clover;  others  being  alsike,  alfalfa,  and  the  pea. 

First-year  clover,  its  roots  being  small  in 
spring,  when  the  beetle  lays  its  eggs,  is  not  known 
to  be  attacked  by  this  borer;  second-year  clover 
is  attacked;  and  clover  that  has  been  allowed  to 
run  for  more  than  two  years  harbors  the  pest  in 
abundance. 

An  affected  plant  finally  wilts  and  dies; 
when  pulled  by  hand  or  by  the  mower  it  breaks 
off  at  the  surface  of  the  ground.  The  roots  of 
such  a  plant  are  burrowed  out  longitudinally 
(Fig.  17),  the  burrows,  with  their  walls  more  or 
less  decayed,  contain  the  excrementitious  parti- 
cles of  the  insect,  and  usually  the  insect  itself  in 
one  or  more  of  its  stages,  tho  the  beetles,  being 
small,  sluggish,  and  inconspicuous  in  color,  are 
easily  overlooked.  Small  cylindrical  holes  thru 
the  sides  of  the  roots  are  characteristic  of  this 
species,  as  indicating  the  emergence  of  beetles. 

The  amount  and  rapidity  of  injury  depend 
not  only  upon  the  number  of  insects  present  but 
also  upon  the  amount  of  moisture  received  by  the  plant.  In  dry 
weather  the  plant  succumbs  quickly  to  the  borer,  but  in  wet  weather 
the  plant,  tho  weakened,  may  continue  to  survive.  Injured  plants  are 
liable  to  die  late  in  June  or  early  in  July,  after  cutting ;  tho  with  plenty 
of  rain  many  of  the  crippled  plants  may  live  until  winter.  In  1893 
and  1894  the  root-borer,  in  combination  with  the  leaf-weevil  and  dry 
weather,  caused  a  general  failure  of  the  clover  crop  in  Michigan. 

The  borer  is  said  to  be  responsible  for  an  irregular,  imperfect 
blooming  of  the  clover  or  a  failure  to  bloom  at  all.  If  the  plants  sur- 
vive, thanks  to  copious  rains,  the  yield  of  seed  is  liable  to  be  almost 
nothing.  In  central  Illinois  the  root-borer  is  generally  distributed,  but 


FIG.  17. — Clover  Root- 
borer,  Hylastinus  ob- 
scurus;  work  of  insect. 
(Webster,  Circ.  67,  Bur. 
Ent.,  U.  S.  Dept.  of  Ag- 
riculture.) 


166 


BULLETIN  No.  134 


[April, 


is  not  a  pest  as  yet,  tho  Mr.  J.  A.  West,  assistant  to  the  State  Ento- 
mologist, found  alsike  injured  by  it  at  Monticello  in  1907. 


FIG.  18. 


FIG.  19. 


FIG.  20. 


Clover  Root-borer,  Hylastinus  obscurus:  Fig.  18,  beetle;   Fig.  19,  larva;  Fig.  20,  pupa. 
Greatly  enlarged.     (Webster,  Circ.  67,  Bur.  Ent.,  U.  S.  Dept.  of  Agriculture.) 

Stages. — The  beetle  (Fig.  18)  is  small — at  most  only  2.5  mm.  in 
length— dark  brown  or  blackish,  cylindrical,  hard-bodied  and  hairy. 
The  elytra,  or  wing-covers,  often  have  a  reddish  tinge,  and  are  coarsely 
punctate ;  and  the  head  and  pronotum  are  more  finely  punctate,  the  lat- 
ter bearing  sparse  long  hairs.  The  tibiae  have  large  teeth  near  the  outer 
end. 

The  egg  is  minute,  tho  visible  to  the  naked  eye,  white,  and  elliptical, 
with  a  smooth,  shining  surface. 

The  larva  (Fig.  19)  is  stout,  white,  with  yellow  head  and  brown 
mouth  parts,  footless,  and  3  mm.  long  when  full  grown. 

The  pupa  (Fig.  20)  is  white,  with  a  pair  of  spinelike  projections 
at  the  extremity  of  the  abdomen,  and  another  pair  on  the  top  of  the 
head.  The  pronotum  shows  a  feeble  median  ridge  and  bears  a  few 
scattering  bristles. 

Life  History  and  Habits. — There  is  but  one  generation  a  year.  In 
Ohio,  where  Webster  worked  out  the  life  history,  the  insect  winters  in 
clover  roots  as  a  beetle  and  also,  tho  less  commonly,  as  a  larva,  the 
latter  pupating  in  spring.  The  beetles  leave  the  roots  during  May  and 
fly  about.  The  eggs  are  laid  mostly  from  May  15  to  June  20  in  cavi- 
ties eaten  out  by  the  females  in  the  crown  of  the  plant  or  down  on  the 
sides  of  the  roots.  In  each  cavity  the  female  lays  several  eggs.  Mr. 
G.  C.  Davis  found  females  laying  eggs  inside  the  root,  in  the  burrows, 
the  eggs  being  packed  into  the  dead  wall  of  the  burrow  and  covered, 
with  refuse.  The  larvae,  the  first  of  which  hatch  late  in  May,  feed  for 
a  time  where  they  hatched,  then  tunnel  along  the  roots/making  one  or 
more  longitudinal  galleries  with  occasional  side  branches,  and  filling 
the  burrows  with  excrement.  The  pupa  is  found  at  the  end  of  a  bur- 
row. Most  of  the  larvae  pupate  before  the  first  of  August  and  most  of 
the  pupae  transform  to  beetles  before  the  first  of  October.  The  beetles 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  167 

remain  in  the  roots, 'however,  until  the  following  spring,  feeding  mean- 
while, when  they  are  not  dormant. 

In  Ohio,  according  to  Webster,  larvae  and  adults  can  be  found  at 
almost  any  time  of  the  year,  tho  the  beetles  are  rare  in  July.  Pupae 
are  most  common  in  July,  but  occur  in  August  and  even  up  to  the  mid- 
dle of  November,  and  a  few  pupae,  newly  formed,  are  met  with  in  early 
spring.  Eggs  have  been  found  as  late,  or  as  early,  as  September  18  in 
Michigan. 

Most  of  our  articles  on  this  insect  have  simply  been  based  on  the 
excellent  accounts  that  Riley,  Webster,  and  G.  C.  Davis  published,  and 
the  species  needs  more  study  than  it  has  received. 

Here  in  central  Illinois  the  life  history  and  habits  are  as  Webster 
found  them  to  be  in  Ohio. 

September  9  a  pair  of  the  beetles  were  observed  in  coitu  in  one 
of  our  cages.  The  conditions  were  not  quite  natural,  however,  for  I 
had  taken  the  beetles  from  roots  and  put  them  on  potted  clover;  out- 
of-doors  they  probably  would  not  have  left  the  roots  until  spring.  As 
soon  as  they  were  placed  on  the  plant,  September  8,  they  began  to 
burrow  into  the  crown;  they  mated  the  day  after;  October  3,  a  long 
burrow  was  found,  containing  several  larvae  at  its  lower  end,  but  no 
eggs;  one  of  the  parent  beetles  was  still  alive  on  November  21. 

Only  one  natural  enemy  of  the  clover  root-borer  has  been  put  on 
record — a  telephorid  larva,  probably  Telephones  bilineatus  Say,  men- 
tioned by  Riley  as  preying  on  the  larva  of  the  borer. 

Control. — A  badly  infested  field  should  be  plowed  as  soon  as  pos- 
sible after  the  removal  of  the  hay  crop,  in  order  to  starve  the  grubs  by 
drying  out  the  roots.  The  plowing  must  not  be  delayed,  for  early  in 
July  (latitude  of  Ohio,  Webster)  the  larvae  begin  to  pass  into  the  qui- 
escent, or  pupa,  stage,  in  which  they  take  no  food;  then  they  would 
doubtless  transform  and  emerge  as  beetles  in  some  numbers  in  spite 
of  plowing. 

In  Ontario,  Can.,  the  value  of  clover  as  a  green  fertilizer  is  so 
generally  appreciated  that  the  farmers  do  not  hesitate  to  plow  the 
clover  under  at  the  first  signs  of  the  presence  of  the  root-borer. 
(Fletcher.) 

Another  thing:  Red  clover  should  not  be  permitted  to  straggle 
along  after  the  second  year  to  furnish  a  nursery  for  this  pest  and 
others. 

Fertilizers  do  not  kill  the  root-borer  and  will  not  save  the  plant — 
so  Mr.  G.  C.  Davis  concluded  from  his  experiments  with  nitrate  of 
soda,  muriate  of  potash,  and  kainit.  Generally  speaking,  fertilizers  as 
used  against  a  root-feeding  insect  act  more  by  stimulating  the  plant 
than  by  affecting  the  insect  directly. 

Hylastinus  obscurus  Marsh. 

1879.  Riley,  C.  V.— Rep.  [U.  S.]  Comm.  Agr.,  1878,  pp.  248-250. 

1880.  Lintner,  J.  A.— Thirty-ninth  Rep.  N.  Y.  State  Agr.  Soc., 

1879,  pp.  41,  42. 


168  BULLETIN  No.  134  [April, 

1894.     Davis,  G.  C— Bull.  No.  116,  Mich.  Agr.  Exper.  Sta.,  pp. 

41-47. 
1896.     Webster,  F.  M.— Bull.  No.  68,  Ohio  Agr.  Exper.  Sta.,  pp. 

31-33. 
1899.     Webster,  F.  M.— Bull.  No.  112,  Ohio  Agr.  Exper.  Sta.,  pp. 

143-149. 
1905.     Webster,  F.  M.— Circ.  No.  67,  U.  S.  Dept.  Agr.,  Bur.  Ent, 

pp.  1-5. 


CLOVER  HAY-WORM 

Hypsopygia  costalis  Fab. 

(Pyralis  costalis,  Asopia  costalis} 

The  clover  hay-worm  works  in  stacked  or  stored  clover,  eating 
much  of  it,  and  contaminating  much  more  with  webs  of  silk  and  parti- 
cles of  excrement,  making  the  hay  unfit  for  fodder. 

This  species,  described  as  long  ago  as  1775,  has  been  sufficiently 
infrequent  in  England  to  be  valued  by  the  collector.  It  inhabits  cen- 
tral and  southern  Europe,  northern  Asia,  northern  Africa,  and  a  large 
part  of  North  America.  In  this  country  its  destructive  work  has  been 
seen  in  New  Hampshire,  Massachusetts,  Connecticut,  New  York, 
Maryland,  West  Virginia,  North  Carolina,  Ohio,  Indiana,  Illinois,  Ken- 
tucky, Tennessee,  Alabama,  Kansas,  Missouri,  Iowa,  Nebraska,  Michi- 
gan, and  in  Ontario,  Canada. 

In  Illinois  the  species  is  widely  distributed,  according  to  the 
records  of  the  State  Entomologist,  and  has  done  no  little  damage  in 
various  parts  of  the  state. 

Injury. — The  larvae  attack  the  bottom  of  a  clover  stack  to  a  height 
of  two  feet  or  more  from  the  ground ;  similarly,  in  the  barn,  they 
occur  near  the  floor.  They  interweave  the  hay  with  white  silken  webs, 
intermixed  with  black  pellets  of  excrement  resembling  coarse  grains  of 
gunpowder;  they  reduce  much  of  the  hay  to  chaff,  and  their  webs 
give  the  hay  the  appearance  of  being  mouldy ;  in  fact,  such  hay  actu- 
ally becomes  mouldy  if  it  has  been  lying  near  the  ground.  This  hay  is 
refused  by  horses  and  cattle  and  is  fit  only  to  be  burnt.  When  the  hay 
is  removed,  swarms  of  wriggling  brown  caterpillars  are  left. 

The  pest  evidently  prefers  dry  clover  hay.  In  mixed  clover  and 
timothy,  the  former  is  eaten  and  the  latter  is  left,  altho  50  percent  of 
such  hay  may  be  damaged  when  the  hay  is  three  quarters  timothy 
(Webster).  One  writer,  it  should  be  said,  has  reported  serious  dam- 
age to  pure  timothy  in  Kentucky.  Webster  reared  the  larvae  on  grow- 
ing clover  heads,  in  the  insectary,  and,  furthermore,  obtained  the  moth 
in  large  numbers  (June  3  to  July  15)  from  masses  of  dead  grape 
leaves  taken  May  5  on  the  ground  in  a  vineyard.  In  summer  the 
caterpillars  are  confined  to  the  old  unfed  hay,  and  the  infestation  is 
worst  on  hay  that  has  lain  over,  year  after  year. 


1909] 


THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA 


169 


FIG.    21. — Clover   Hay-worm,    Hypsopygia   costalis,   larva. 
Greatly  enlarged. 


Osborn  mentions  Pyralis  farinalis,  as  well  as  H.  costalis,  as  injur- 
ing stored  clover  hay  in  Iowa. 

Stages. — The  full-grown  caterpillar  (Fig.  21)  is  three  quarters  of 
an  inch  long,  and  dull  brown  with  an  olive  tinge  usually,  tho  some  of 
the  largest  larvae  re- 
tain the  pale  color  of 
the  young  larvae.  The 
head,  shield,  and  cau- 
dal plate  do  not  turn 
dark  until  after  the 
last  moult,  according 
to  Riley.  The  thorac- 
ic segments  are  much 
wrinkled,  and  most 
of  the  remaining  seg- 
ments are  each  di- 
vided by  a  transverse 

groove  into  two  subsegments,  the  anterior  of  which  is  the  larger.  On 
each  segment  are  several  smooth  shining  areas,  each  bearing  a  fine 
white  hair. 

The  cocoon  is  half  an  inch  in  length,  oblong-oval,  and  composed 
of  white  silk,  intermingled  with  excrement  and  bits  of  hay. 

The  chrysalis,  as  described  by  Riley,  is  honey-yellow,  with  the 
segments  and  members  clearly  defined  by  the  darker  color  of  the  "in- 
sections." 

The  moth  (Fig.  22)  is  small — the  largest  specimens  spreading  22 
mm. — and  has  silky  wings  tinged  with  purplish  above,  margined  with 

orange,  and  fringed  with  golden  yel- 
low. On  each  of  the  upper  wings  are 
two  large  golden  spots  so  situated  as 
to  divide  the  front  margin  of  the  wing 
into  thirds;  each  of  these  spots  con- 
tinues backward  to  the  hind  margin 
of  the  wing  as  a  narrow  lilac  line.  On 
each  hind  wing  are  two  wavy  trans- 
verse straw-colored  lines,  one  across 
the  middle  of  the  wing,  and  the  other 
half-way  between  the  first  line  and  the 
base  of  the  wing.  Underneath,  the 

wings  are  pale  yellowish  with  the  markings  indistinct.  Head  and  legs 
straw-colored ;  antennae  and  palpi  pale  orange,  tinged  with  lilaceous. 

Life  History  and  Habits. — In  Missouri  and  Ohio  there  are  two 
generations  a  year  and  apparently  more  or  less  of  a  third  brood.  In 
winter,  larvae  of  all  sizes  are  to  be  found  in  clover  hay.  In  Ohio,  Web- 
ster found  pupae  no  earlier  than  May  25 ;  moths  emerged  June  12  and 
laid  eggs  June  13  to  17,  other  moths  issuing  from  June  3  to  July  15; 
young  larvae  (very  small  to  half  grown)  occurred  July  1 ;  larvae  and 
pupae  were  seen  August  6 ;  and  adults  of  the  second  generation  began 


FIG.  22. — Clover  Hay-worm, 
Hypsopygia  costalis,  moth. 
Twice  natural  width. 


170  BULLETIN  No.  134  [April, 

to  emerge  August  8 — larvae  from  these  being  found  August  15.  In 
Connecticut,  pupae  and  many  grown  larvae  occurred  June  7  (Britton)  ; 
a  pupa  formed  June  5  gave  the  moth  June  18;  most  of  the  moths  dis- 
appeared by  July  15  (in  a  certain  barn)  ;  the  first  larvae  of  the  second 
generation  were  taken  in  a  stack  of  clover  September  1 ;  and  larvae 
were  not  found  in  barns  until  two  or  three  weeks  later. 

In  Illinois  the  hay-worm  is  destructive  in  winter  and  spring,  as 
elsewhere.  The  records  of  the  State  Entomologist  refer  to  its  occurrence 
January  6  at  Griggsville ;  February  4,  Midland  City ;  February  18, 
Shelbyville;  March  25,  Deland;  April  6,  Fillmore;  May  21,  Ridge- 
farm;  and  May  27,  Parkersburg.  A  correspondent  in  Shelbyville  re- 
ported the  caterpillar  from  cheat,  mixed  with  wheat  and  timothy. 

The  office  notes  include  a  great  many  records  of  the  capture  of 
the  moths  from  June  2  onward.  June  6,  two  moths,  numerous  pupae, 
and  a  great  many  larvae  were  present  in  a  box  of  infested  clover  hay 
received  from  Parkersburg;  and  other  moths  issued  June  10,  19,  and 
20.  Dr.  Forbes  recorded  moths  of  this  species  as  being  abundant  July 
10  to  20  and  far  less  abundant  July  28.  They  disappear  about  the  last 
of  July — those  of  the  first  generation — after  flying  thruout  the  months 
of  June  and  July.  The  moths  of  the  second  brood  appear  a  little  be- 
fore the  middle  of  August.  Moths  are  constantly  seen  from  that  time 
until  the  middle  of  October,  but  the  last  of  these  perhaps  represent  a 
third  generation. 

In  the  breeding-cage,  eggs  may  be  laid  on  growing  clover  heads, 
as  appears  from  Webster's  experiments,  hence  it  is  possible  that  the 
same  thing  occurs  in  the  field. 

Out-of-doors,  the  moths  are  seen  flitting  about  clover  stacks  at 
dusk  or  in  cloudy  weather  (June  29,  Ohio).  At  night  they  often  get 
into  houses  and  fly  toward  the  lights. 

The  caterpillars,  of  all  sizes,  can  be  found  at  any  time  during  the 
winter,  and  in  a  barn  they  are  active  when  everything  outside  is  frozen. 
Warmth  and  moisture  are  greatest  at  the  bottom  of  the  clover,  and 
there  these  caterpillars  flourish.  When  you  pick  them  up  they  are 
likely  to  wriggle  out  of  your  hand ;  they  can  wriggle  backward  as 
well  as  forward.  They  spin  a  lot  of  silk,  and  construct  little  silken 
cases  for  themselves,  as  do  the  clothes  moths ;  they  are  continually 
spinning,  and  are  often  seen  hanging  from  a  thread  of  silk.  These 
caterpillars  are  gregarious,  or  sociable ;  they  gather  together  while  they 
are  feeding,  tho  they  separate  and  wander  when  full  grown  and  ready 
to  make  their  cocoons. 

No  insect  enemies  of  this  pest  are  as  yet  known. 

Control. — In  a  barn,  old  refuse  clover-hay  should  be  removed  and 
burned  if  this  insect  is  present,  before  new  clover  is  put  in.  A  stack 
of  clover  hay  should  be  raised  above  the  ground  on  a  foundation  of 
logs  or  rails,  in  order  to  keep  the  bottom  of  the  stack  as  dry  and  cool 
as  possible.  It  has  been  found  that  salting  the  hay  at  the  bottom  for 
two  or  three  feet  will  preserve  it  from  injury.  Some  farmers  habitu- 
ally salt  their  clover  hay,  using  about  two  quarts  of  salt  to  the  ton. 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  171 

Webster's  experiments  indicate  that  the  caterpillars  can  be  killed 
at  once  in  a  clover  stack  by  the  use  of  pyrethrum.  He  had  five  tons 
of  clover  restacked,  dusting  it  with  this  insect  powder,  using  ten 
pounds  of  pyrethrum  to  fifty  pounds  of  flour,  and  found  in  a  sample 
of  the  hay  that  the  majority  of  the  caterpillars  were  dead  the  day  after. 

Britton,  in  Connecticut,  tried  bisulfid  of  carbon  in  a  stack  and 
hydrocyanic  acid  gas  in  a  barn,  but  in  both  instances  the  clover  had 
become  packed  so  solidly  that  only  a  few  caterpillars — those  on  the 
outer  part  of  the  heap — were  killed  by  the  treatment. 

We  need  to  know  more  about  the  life  history  and  habits  of  this 
insect  notwithstanding  the  large  number  of  articles  that  have  been 
written  on  the  species,  for  these,  with  a  few  exceptions,  add  nothing 
to  Riley's  original  account  of  1874. 

Hypsopygia  costalis  Fab. 

1874.     Riley,  C.  V.— Sixth  Rep.  Ins.  Mo.,  pp.  102-107. 
1891.     Webster,  F.  M.— Insect  Life,  Vol.  IV.,  pp.  121,  122. 
1894.     Davis,  G.  C— Bull.  No.  116,  Mich.  Agr.  Exper.  Sta.,  pp. 

56-58. 

1896.     Lintner,  J.  A.— Eleventh  Rep.  Ins.  N.  Y.,  pp.  145-151. 
1901.     Britton,  W.  E. — Twenty- fourth  Rep.  Conn.  Agr.  Exper. 

Sta.,  1900,  p.  314. 

CLOVER  LEAF-MIDGE 

Dasyneura  trifolii  Low 

(Cecidomyia  trifolii) 

This  midge  deserves  some  attention  on  account  of  its  conspicuous 
effects  on  the  leaflets  of  white  clover,  the  leaflet  being  folded  in  halves 
along  the  midrib  to  form  a  sort  of  pod,  which  turns  yellowish  and  at 
length  brownish.  Within  this  pod  can  be  found  white  or  orange  mag- 
gots, or  silken  cocoons.  The  maggots  change  to  minute  flies — so  small 
and  inconspicuous  as  to  interest  only  a  specialist. 

The  economic  importance  of  the  leaf-midge  is  small,  however, 
and  nothing  has  been  added  to  our  published  knowledge  of  the  species 
since  Comstock's  account  of  1880.  Some  new  information  appears  in 
the  present  paper. 

The  species,  long  known  in  Europe,  has  been  recorded  from 
Washington,  D.  C. ;  it  occurs  also  in  Illinois,  and  in  all  probability  is 
present  in  many  other  parts  of  the  country. 

Food  Plants. — The  leaf-midge  feeds  on  white  clover.  In  Europe 
it  has  been  said  to  affect  the  undermost  root-leaves  of  red  clover,  but 
I  have  not  as  yet  been  able  to  find  it  on  that  plant  in  this  region. 

The  maggot  does  not  fold  the  leaflet;  the  egg  is  laid  before  the 
leaflet  has  opened  out,  and  after  the  larvae  begin  to  work  the  leaflet 
remains  closed.  It  grows  to  a  normal  size,  however,  (PI.  I.,  Fig.  4) 
and  continues  to  be  green  for  a  time,  but  eventually  turns  yellowish 
near  the  midrib,  where  the  leaflet  bulges  out  here  and  there,  blisterlike. 


172  BULLETIN  No.  134  [April, 

As  the  gall  gets  older  the  blistered  areas  become  specked  with  brown, 
and  finally  the  entire  gall  turns  brown  and  the  leaflet  dies.  Inside  the 
pod  are  the  maggots — white  or  orange,  according  to  age — and  the 
white  cocoons.  The  eggs  are  to  be  found  only  between  the  folded 
halves  of  the  smallest  leaflets,  near  the  ground. 

An  affected  leaflet  continues  to  grow,  and  its  forage  value  is 
scarcely  diminished,  but  its  death  is  hastened  a  little  by  the  maggots. 
There  is  no  effect  upon  the  plant  as  a  whole;  when  only  one  leaflet  of 
a  leaf  is  affected  by  the  insect,  the  other  two  remain  healthy  for  an  in- 
definite time,  but  all  three  will  at  length  wilt  and  die  a  little  pre- 
maturely. 

It  can  hardly  be  said  that  this  insect  actually  injures  white  clover, 
taking  everything  into  consideration. 

Stages. — The  egg  has  not  been  described  before.  It  is  like  that  of 
many  other  common  midges,  being  elliptico-cylindrical  with  a  slight 
curvature,  colorless  and  translucent  when  laid,  but  showing  an  internal 
red  spot  on  the  second  day — not  before — and  becoming  pale  orange  in 
color.  Length,  0.3  mm. ;  width,  0.075  mm., — on  an  average.  Several 
eggs  are  laid,  side  by  side  usually,  as  in  Plate  I.,  Fig.  5,  in  which  the 
variation  in  the  length  of  the  eggs  is  to  be  laid  to  the  midge  instead  of 
to  the  artist. 

The  newly  born  larva  is  colorless  and  transparent,  and  0.27  mm. 
in  length;  soon  it  becomes  white;  when  old  it  is  orange  (PL  I.,  Fig.  6), 
and  when  full  grown  its  length  is  1.5  to  2  mm.  The  skin  is  coarsely 
granulate.  The  spiracular  tubercles  are  arranged  precisely  as  in  the 
larva  of  the  clover  seed-midge — in  fact,  this  arrangement  is  the  same 
in  several  species  that  I  have  examined.  The  form  of  the  sternal 
spatula  (PL  I.,  Fig.  7)  is,  however,  different  from  that  of  D.  leguminic- 
ola,  the  only  species  likely  to  be  confused  with  this  one  as  it  occurs  on 
clover. 

The  cocoon  is  oval  in  general  outline,  and  1.5  mm.  long.  Often 
it  is  flattened  a  little  from  contact  with  the  leaflet  or  with  other  co- 
coons. 

The  pupa,  orange  in  color,  has  a  darker  median  ventral  stripe,  and 
blackish  eyes,  as  Comstock  says.  The  anterior  border  of  the  pro- 
thorax  is  deeply  notched,  and  there  are  two  long,  excurved,  meso- 
thoracic  horns. 

Comstock  gave  a  translation  of  the  original  description  of  this 
midge,  which  need  not  be  repeated  here.  Rearing  the  midge  from 
white  clover,  there  is  no  difficulty  in  determining  the  species.  Catch- 
ing it  on  the  wing,  the  leaf-midge  needs  to  be  distinguished  from  the 
seed-midge,  which  it  resembles.  Figures  3  and  8  of  Plate  I.  show  the 
differences  between  the  two  species.  The  leaf-midge  (Fig.  8)  is  the 
smaller  of  the  two,  the  female  measuring  1.6  mm.  in  length.  Both 
species  have  the  red  abdomen,  but  the  dorsal  bands  of  black  scales  are 
much  larger  and  denser  in  trifolii  than  in  leguminicola,  and  the  scales 
do  not  rub  off  so  easily,  so  that  the  abdomen  in  the  former  species  is 
usually  blackish.  In  addition,  the  leaf-midge  has  14  or  15  antenna! 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  173 

segments,  as  against  16  or  17  in  the  seed-midge.  The  male,  distin- 
guishable from  the  female  by  the  large  clasping  organs  at  the  end  of 
the  abdomen,  is  also  smaller  than  the  male  of  the  seed-midge. 

Life  History. — The  podlike  galls  (PI.  I.,  Fig.  4)  of  the  leaf-midge 
are  common  on  white  clover  thruout  the  growing  season,  during  which 
the  insect  in  one  or  another  of  its  stages  can  always  be  found  in  some 
of  the  galls.  Usually  several  stages  in  the  development  of  the  insect 
are  represented  at  the  same  time  in  a  single  gall.  Frequently  one  to 
six  individuals  inhabit  the  same  gall,  and  there  may  be  more ;  I  know 
of  twenty  eggs  being  deposited  by  a  single  female  on  one  leaflet. 
Larva*  from  eggs  laid  at  the  same  time  do  not  all  develop  equally ; 
some  of  them  outdistance  the  rest,  and  when  the  gall  is  crowded  with 
the  maggots,  some  of  them  die  off  in  the  competition  for  nourish- 
ment. 

The  earliest  date  that  I  have  recorded  for  the  galls  is  June  21,  at 
which  time  larvae  and  cocoons  were  present;  thereafter  I  found  the 
species  in  various  stages  every  few  days  up  to  October  5,  on  which 
date  larvae  were  common.  The  latest  eggs  and  larvae  are  killed  by  the 
frost,  along  with  the  leaves  which  they  inhabit.  This  fact  in  connec- 
tion with  what  we  know  about  the  habits  of  the  species  warrants  the 
inference  that  it  probably  winters  in  the  cocoon,  tho  possibly  as  a  fly. 

My  observations  indicate  four  full  broods  a  year  in  this  place, 
with  scattering  and  ill-fated  members  of  a  fifth  brood.  Each  genera- 
tion requires  about  one  month,  on  an  average,  for  its  development.  In 
the  field  the  broods  overlap  enough  to  make  their  separation  by  field 
observations  a  little  difficult.  Yet  there  are  times  when  almost  all  the 
galls  are  empty,  indicating  an  interval  between  two  bropds,  when  the 
species  is  represented  almost  entirely  by  winged  adults.  Thus,  Au- 
gust 14,  1903,  when  I  examined  a  great  number  of  recently  made  galls, 
I  found  85  without  living  contents,  tho  remnants  of  cocoons  were 
often  present;  9  with  cocoons  (one  to  four  in  each  instance)  ;  2  with 
full-grown  or  large  larvae;  and  2  with  larvae  that  had  just  hatched. 
Again,  August  15,  1907,  I  opened  several  hundred  of  the  galls  and 
found  nearly  all  of  them  to  contain  cocoons  or  full-grown  larvae ;  only 
one  or  two  had  white  larvae,  and  very  many  of  the  galls  were  empty, 
tho  not  more  than  a  month  old.  Thus  a  break  between  two  genera- 
tions occurred  about  August  15  in  two  years. 

Eggs  laid  August  1  gave  six  larvae,  the  flies  from  which  issued 
August  22;  this  is  the  shortest  life  history  that  I  have  found  for  this 
species.  The  egg  period  is  six  days  as  a  rule;  thus,  eggs  laid  August 
13  (2:45  to  3:15  p.  m.)  hatched  August  19  (at  noon).  The  period 
in  the  cocoon  varies.  From  two  cocoons  made  August  3,  the  imagines 
emerged  August  13 ;  in  several  other  instances,  nine  days  was  the 
period.  On  the  other  hand,  a  larva  that  was  making  a  cocoon  August 
5  did  not  give  the  adult  until  August  27. 

Habits. — The  midges  can  be  obtained  simply  by  picking  the  galls 
and  keeping  them  on  damp  sand  or  cotton- wool.  A  better  way,  how- 
ever, is  to  transplant  such  plants  as  bear  the  galls,  because  the  leaves 
do  not  keep  fresh  very  long  after  being  picked. 


174  BULLETIN  No.  134  [April, 

To  get  the  eggs  and  the  subsequent  stages  it  is  only  necessary  to 
turn  a  lot  of  the  midges  loose  on  potted  white  clover  under  a  lamp 
chimney  (the  narrow  cylindrical  kind)  covered  at  the  top  with  net- 
ting, making  sure  that  the  plant  bears  some  young  unopened  leaves. 
It  is  best,  also,  to  cut  off  most  of  the  old  leaves,  especially  in  order  to 
facilitate  observation. 

These  little  flies  mate  readily  under  such  conditions,  and  lay  eggs 
freely,  as  I  have  several  times  observed.  After  coition,  which  may 
not  last  longer  than  a  minute,  oviposition  occurs  within  an  hour  or  so. 
The  female  either  drops  to  the  ground  or  alights  on  the  plant  and 
walks  downward.  In  either  event  she  finds,  after  more  or  less  explora- 
tion, a  young  leaflet  still  folded  in  halves.  Standing  at  the  base  of 
this,  she  wriggles  her  long  flexible  ovipositor  in  between  the  two  con- 
tiguous faces  of  the  leaflet  as  far  as  possible ;  at  intervals  a  slight  wave 
of  distention  passes  back  along  the  ovipositor,  indicating  probably  the 
passage  of  an  egg.  Usually  several  eggs  are  laid  on  the  same  leaflet — 
sometimes  a  dozen  or  more.  After  many  eggs  are  laid,  the  abdomen  of 
the  female  is  noticeably  smaller. 

In  some  way  the  insect  prevents  the  leaflet  from  opening  out.  The 
larva  is  quite  unable  to  fold  a  leaflet  that  has  already  spread  out.  If 
placed  on  such  a  leaf  the  larvae  cannot  even  hold  on  to  it,  and  rolls  oft". 
Like  other  midge  larvae,  they  require  some  tight  crevice  in  which  to 
develop. 

Like  them  also,  the  maggots  of  the  clover  leaf-midge  are  very 
sensitive  to  moisture,  contracting  and  becoming  motionless  when  it  is 
dry,  and  resuming  activity  when  it  is  moist.  Dryness  prolongs  the 
period  of  development  and  retards  the  emergence  of  the  fly.  The 
long  record  just  given  6f  twenty-two  days  from  cocoon-making  to 
emergence  was  due  in  some  measure  to  dryness.  The  larva  found 
making  a  cocoon  August  5,  was  put  into  a  small  glass-covered  box  and 
pressed  up  against  the  glass  by  means  of  dry  cotton- wool,  so  that  I 
could  watch  the  process  of  cocoon  formation  under  the  microscope. 
The  larva  spun  for  awhile,  and  then  left  its  cocoon  unfinished  and 
wandered  about,  but  it  was  contracted  and  motionless  August  6  to  11. 
On  the  latter  date  the  cotton  was  moistened,  and  soon  the  larva  began  to 
wriggle  about  in  all  directions,  away  from  the  light,  and  kept  this  up  all 
day.  Coming  to  rest  again,  the  larva  contracted  without  making  a 
new  cocoon,  and  gave  an  imago  August  27.  The  larva  often  pupates 
without  making  a  cocoon,  if  taken  out  of  its  gall. 

The  cocoon  is  evidently  composed  of  silken  threads,  as  Comstock 
said.  Under  the  microscope  the  thread  can  be  seen  to  issue  from  the 
mouth  of  the  larva,  which  swings  the  fore  part  of  the  body  to  and  fro 
as  it  spins.  This  fact  is  mentioned  to  counteract  the  old  statement 
that  the  cocoon  is  an  exudation  around  the  body  of  the  larva. 

The  leaf-midge  is  not  without  natural  enemies.  I  have  found  the 
larvae  and  pupae  of  a  chalcid  in  the  galls  among  the  midge  larvae.  The 
chalcid  is  not  common ;  I  found  it  in  only  1  percent  of  the  galls,  out 
of  hundreds  examined.  The  chalcid  larva  might  hastily  be  mistaken 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  175 

for  one  of  the  midge  larvse,  as  it  has  much  the  same  size  and  color — 
white  or  orange.  Its  body  is  not  so  blunt  as  that  of  the  maggots,  how- 
ever, and  tapers  anteriorly.  Furthermore,  the  chalcid  larva  is  far  more 
active  than  a  midge  larva.  While  the  latter  wriggles  about  sluggishly 
and  aimlessly,  the  former  wriggles  along  hurriedly,  as  if  it  had  some 
end  in  view.  A  few  times  I  have  seen  a  chalcid  larva  attack  and  feed 
upon  a  maggot  of  the  midge,  it  being  predaceous  instead  of  parasitic. 
The  chalcid  becomes  a  naked  pupa  within  the  gall,  among  any  of  the 
maggots  that  may  have  escaped  its  attacks. 

The  clover  leaf-midge  needs  no  discussion  from  the  point  of  view 
of  control.  Where  the  clover  is  frequently  pastured  or  cut  (as  on 
lawns)  it  is  hard  to  find  any  signs  of  the  leaf-midge. 

Dasyneura  (Cecidomyia)  trifolii  Low 

"  1880.     Comstock,  J.  H.— Rep.   [  U.  S.  ]   Comm.  Agr.,  1879,  pp. 
197-199. 


CLOVER  CALLIPTERUS 
Callipterus  trifolii  Monell 

This  aphid  is  common  in  our  clover  fields  every  year,  but  has  not 
been  destructive  as  yet.  It  is  far  less  numerous  than  the  large  green 
aphid,  Macrosiphum  pisi,  and  is  not  wide-spread  and  gregarious  like 
that  species,  but  is  scattered,  and  rather  solitary  in  habit. 

C.  trifolii,  as  found  on  clover,  will  be  recognized,  generally 
speaking,  as  a  small  yellowish  green  or  yellow  species  with  six  longi- 
tudinal rows  of  dark  tubercles  on  the  abdomen. 

This  species  has  received  almost  no  mention  in  our  literature, 
largely  because  it  has  done  nothing  to  attract  attention.  .  The  material 
which  we  studied  was  determined  tentatively  by  me  from  the  original 
description,  and  positively  by  the  author  of  the  species,  to  whom  speci- 
mens were  sent  by  Mr.  J.  J.  Davis. 

Callipterus  trifolii  was  described  from  Washington,  D.  C.,  by 
Monell,  who  found  it  again  in  Missouri.  It  is  common  in  Illinois,  and 
is  reported  authentically  from  Iowa,  Kansas,  Minnesota,  North  Da- 
kota, New  York,  Delaware,  and  Virginia. 

Descriptions. — The  following  descriptions,  sufficiently  detailed  for 
the  recognition  of  the  species,  and  supplementary  to  the  original  de- 
scription, are  adapted  from  manuscript  descriptions  made  by  J.  J. 
Davis,  in  cooperation  with  Monell. 

The  viviparous  females  (whether  winged  or  not)  are  pale  yellow- 
ish green.  Eyes  dark  red  to  brown.  Antennae  pale  greenish  basally, 
dusky  apically,  faintly  imbricate,  and  as  long  as  or  a  little  longer  than 
the  body.  Legs  pale,  dusky  at  the  joints ;  tarsi  blackish.  Abdomen 
with  six  longitudinal  rows  of  dusky  setiferous  tubercles.  Style  globu- 
lar; cornicles  tubercular;  both  a  little  dusky. 

In  the  wingless  viviparous  female  (PI  II.,  Fig.  5)  the  dark  ab- 
dominal tubercles  bear  conspicuous  capitate  hairs,  and  the  length  of 
the  female  averages  1.6  mm. 


176 


BULLETIN  No.  134 


[April, 


The  winged  viviparous  female  (PI.  II.,  Fig.  6)  has  a  row  of  ten 
to  twelve  sensoria  on  the  third  antennal  segment.  Wings  hyaline ; 
veins  dark  brown  to  black,  narrowly  bordered  with  brownish,  with  a 
small  brown  patch  at  the  outer  end  of  each  vein ;  basal  half  of  stigmal 
vein  obsolescent;  discoidals  as  in  the  figure.  The  abdominal  tuber- 
cles of  the  two  inner  rows  are  oblong,  and  each  of  them  bears  two  fine 
setae.  The  remaining  tubercles,  more  or  less  circular,  have  each  but 
one  seta.  Average  length,  1.4  mm. 

The  wingless  oviparous  female  is  at  first  pale  yellow,  but  the  ab- 
domen (excepting  the  last  two  segments)  becomes  progressively 
orange  as  the  eggs  develop  in  the  body,  and  the  orange  color  may 
eventually  extend  over  most  of  the  thorax.  Eyes  black.  The  anten- 
nae do  not  reach  to  the  cornicles,  and  the  third  antennal  segment  has 
eight  or  ten  circular  sensoria.  Hind  tibiae  swollen,  and  with  sensoria. 
Dorsal  abdominal  tubercles  essentially  as  in  the  winged  viviparous 
female.  Average  length,  1.8  mm. 

In  the  winged  male  the  head  and  thorax  are  pale  olivaceous 
green,  and  the  abdomen  pale  yellowish  green,  with  conspicuous  black 
dorsal  spots.  Antennae  black  (excepting  the  first  two  segments)  and 
as  long  as  the  body,  with  sensoria  as  follows:  12-15  on  segment 
three;  2-4  on  four;  3-5  on  five.  Wings  essentially  as  in  the  female. 
The  large  black  oval  setiferous  spots  of  the  abdomen  fall  chiefly  into 
four  rows — two  dorsal  and  two  lateral,  with  scattered  spots  between 
the  former  and  the  latter,  on  each  side.  Style  and  cornicles  dusky. 
Average  length,  1.2  mm. 

The  absolute  lengths  of  the  segments  of  the  antennae  and  legs,  as 
well  as  those  of  the  cornicles,  are,  as  in  other  aphids,  too  variable  to 
be  of  much  importance  as  specific  characters.  The  relative  lengths 
are  more  constant,  however,  and  hence  more  important  for  the  sys- 
tematist.  They  appear  from  the  following  table,  which  consists  of  the 
averages  of  many  measurements  made  from  Urbana  specimens  by  J.  J. 
Davis  and  from  types  of  Mr.  Monell — made  by  himself. 

C.  trifolii 


Ant< 

;nna? 

Cor- 

I 

II 

III 

IV 

V 

VI 

Style 

nicles 

Wingless  viviparous  female 
Winged  viviparous  female 
Winged  viviparous  female, 
Monell's  types 
Wingless  oviparous  female 
Winged  male 

07  mm. 
07 

.05 
.07 
.06 

.05 
.05 

.04 
.05 
.05 

.51 
.51 

.44 
!40 
.51 

34 
.36 

.31 
.19 
30 

.31 

.32 

.28 
.20 
.29 

.15+.  16 
.16+.  16 

.15+.  13 
.13+.  14 
.15+  15 

.17 
.13 

.06 
.06 

.06 
.04 

The  egg,  hitherto  undescribed,  is  much  like  that  of  any  other 
aphid  in  being  elliptical,  0.57  mm.  long,  and  0.25  mm.  broad,  but  has  a 
characteristic  bright  orange-color  when  recently  laid. 


1909] 


THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA 


177 


Life  History,  etc. — This  aphid  winters  as  an  egg  in  the  vicinity 
of  Urbana,  and  I  have  found  as  yet  no  evidence  that  the  female  hiber- 
nates. The  course  of  the  life  history  differs  but  little  from  that  of 
other  aphids.  The  eggs  produce  viviparous  females,  and  these  con- 
stitute the  successive  generations  up  to  the  end  of  the  season,  when 
winged  males  and  wingless  oviparous  females  are  brought  forth  vivip- 
arously.  In  this  species,  a  large  proportion — if  not  the  majority — of 
the  viviparous  females  are  winged. 

Beginning  with  a  viviparous  female  which  issued  from  the  egg 
March  27,  Mr.  R.  L.  Webster  followed  the  successive  generations 
thru  the  season  and  obtained  a  maximum  of  nineteen,  the  final  genera- 
tion appearing  October  18,  in  the  insectary.  The  individuals  of  this 
generation  were  still  very  small  on  November  11,  and  disappeared 
thereafter.  The  more  important  of  R.  L.  Webster's  observations  are 
given  in  the  following  table. 

C.  trifolii 


Genera- 
tion 

Birth 

Maturity                Death 

Days  to 
mature 

Days  of 
life 

Number 
of  young 

1 

Mar.  27 

t 
Apr.  20               May  9 

24 

43 

36 

2 

Apr.   21 

May  3                 May  21 

12 

30               21 

3 

May  6 

May  18               May  26 

12 

20                34 

4 

May  15 

May  30               June  12 

15 

28               25 

5 

May  30 

June  7                June  19 

8 

20                46 

6 

June  7 

June  15               June  21 

8 

14                25 

7 

June  15 

June  22               July  7 

7 

22               55 

8 

June  24 

July  3                  July  3 

9 

9 

13 

9 

July  3 

July  12                July  18 

9 

15 

13 

10 

July  13 

July  18               July  31 

5 

18 

34 

11 

July  19 

July  29               Aug.   3 

10 

15 

23 

12 

July  29 

Aug.  5                 Aug.  22 

7 

24 

70 

13 

Aug.  5 

Aug.   11               Sept.  2 

6 

28 

75 

14 

Aug.   11 

Aug.  21               Sept.   9 

10 

29 

60 

15 

Aug.  21 

Aug.   28               Sept.   11 

7 

21 

36 

16 

Sept.   10 

Sept.  18              Sept.  28 

8 

18 

20 

17 

Sept    19 

Oct.  2                 Oct.  9 

13 

20                 6 

18 

Oct.  2 

Oct.  18                     ? 

16               40+    j          ? 

19 

Oct.  18 

?                           ? 

? 

24+             ? 

Ave 

rages  

10 

22 

34.8 

The  averages  are  made  from  the  first  seventeen  generations.  The 
number  of  young  produced  per  day  by  one  female  ranges  from  none 
to  thirteen,  with  an  average  of  3.7 ;  and  the  bearing  period  of  the 
female  averages  12.1  days. 

Comparing  this  table  with  that  for  M.  pisi  (p.  142)  slight  differ- 
ences are  apparent  in  the  length  of  life  and  the  period  before  "maturity. 
These  differences  are  of  no  weight,  however,  in  view  of  the  great 
variability  of  both  species  in  both  these  respects.  A  few  more  obser- 
vations would  have  changed,  one  way  or  the  other,  these  averages,  which 
are  so  nearly  alike.  The  averages  show,  rather,  that  M.  pisi  and  C. 


178  BULLETIN  No.  134  [April, 

trifolii  agree  essentially  as  regards  the  time  from  birth  to  maturity, 
the  bearing  period,  and  the  length  of  life,  the  number  of  generations 
being  essentially  the  same  in  both  species.  C.  trifolii  produces,  how- 
ever, only  half  as  many  young  per  day  as  M.  pisi  (3.7  young  as  against 
6),  and  this  difference  serves  to  account  for  the  relatively  smaller  num- 
bers of  C.  trifolii  in  the  field  compared  with  M.  pisi. 

Wintered  eggs  hatched  March  27,  28,  and  29,  according  to  our 
notes. 

On  red  clover,  brought  into  the  laboratory  in  November,  and 
grown,  there  were  found,  January  29,  a  large  number  of  the 
orange  oviparous  females,  which  laid  eggs  in  profusion.  The  average 
number  of  eggs  in  the  abdomen  of  the  mother  is  ten,  as  found  by  J.  J. 
Davis. 

The  fungus  Empusa  aphidis  attacks  this  plant-louse  thruout  the 
season,  in  damp  weather,  just  as  it  does  M.  pisi;  and  many  of  the  in- 
sect enemies  of  the  latter  species  attack  C.  trifolii  also. 

Callipterus  trifolii  maintains  its  existence  every  year,  but  has 
always  been  a  sporadic  species. 

Callipterus  trifolii-  Monell. 

1882.     Monell,  J.  T.— Can.  Ent.,  Vol.  XIV.,  p.  14. 

1908.     Davis,  J.  J.— Ann.  Ent.  Soc.  Amer.,  Vol.  I.,  pp.  256-258. 


CLOVER  STEM-BORER 
Languria  mozardi  Latr. 

The  stem-borer  is  of  but  secondary  importance  among  the  in- 
jurious insects  of  clover;  it  has  never  been  a  pest,  so  far  as  I  can 
learn. 

The  slender  yellow  larva  eats  out  the  pith  of  the  clover  stem, 
making  a  long  burrow,  with  brown  discolored  walls.  The  entire  de- 
velopment takes  place  within  the  clover  stem,  and  the  adults  fly  abroad 
as  slender  beetles  with  dark  blue  wing-covers,  and  red  thorax  and 
head. 

Tho  the  beetle  is  well  known  to  collectors,  scarcely  anything  has 
been  published  on  its  life  history  since  Comstock's  brief  account  in 
1880. 

Distribution. — This  species  was  originally  described  from  North 
America,  and  the  genus  Languria  does  not  appear  in  the  catalogs  of 
European  beetles.  In  this  country  L.  mozardi  has  been  reported  from 
Pennsylvania,  the  District  of  Columbia,  Indiana,  Illinois,  Michigan, 
Kansas,  Nebraska,  and  elsewhere.  Generally  speaking,  it  inhabits  the 
middle  and  the  southern  states,  some  of  the  western  states,  and  parts 
of  Canada. 

Food  Plants  and  Injuries. — The  clover  stem-borer  is  by  no  means 
limited  to  red  clover  and  mammoth  clover,  but  feeds  also  on  the  fol- 
lowing plants,  as  C.  M.  Weed,  Chittenden,  and  Webster  found :  wild 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  179 

sweet  clover  (Melilotus  alba),  pink  fleabane  (Erigeron  philadelphi- 
cus),  daisy  fleabane  (E.  ramosus),  mare's  tail  (E.  canadensis),  rag- 
weed (Ambrosia  trifida),  coneflower  (Rudbeckia  laciniata),  yarrow 
(Achillea  mille  folium),  oxeye  daisy  (Chrysanthemum  leucanthe- 
mum),  thistle  (Cnicus  altissimus),  wild  lettuce  (Lactuca  canadensis 
and  L.  Horidana),  bellflower  (Campanula  americana),  nettle  (Urtica 
gracilis  and  U.  dioica)  and  timothy  (Phleum  pratense).  Most  of 
these  are  Composite,  it  will  be  noticed,  and  nearly  all  are  weeds. 

Injury. — The  beetles  do  not  lay  their  eggs  in  seedling  clover,  but 
find  clover  that  is  more  than  one  year  old  and  select  only  the  larger 
stems  of  that. 

By  autumn,  red  clover  sown  in  spring  has  developed  stems  of  con- 
siderable size,  and  the  beetles  are  present — but  they  do  not  lay  eggs  in 
autumn,  in  my  experience.. 

The  larva,  by  eating  the  pith,  hollows  out  the  clover  stem,  making 
a  long  burrow,  the  walls  of  which  turn  brown.  By  cutting  stems 
across,  beginning  near  the  ground,  and  looking  at  the  cut  ends,  one 
can  see  whether  the  pith  is  white  and  solid  or  whether  it  has  been 
eaten  out  by  this  borer.  The  larvae  eat  usually  nothing  but  the  pith, 
which  happens  to  be  the  part  that  the  plant  can  best  afford  to  lose. 

Comstock  wrote,  "While  they  do  not  kill  the  stem  outright,  they 
gradually  weaken  it  and  eventually  cause  its  destruction,  having  also, 
of  course,  a  very  injurious  effect  upon  the  maturing  of  the  seed."  Un- 
doubtedly the  insect  is  injurious,  but  it  is  not  so  injurious  as  might  be 
supposed.  The  loss  of  the  pith  may  affect  the  nutrition  of  the  plant 
to  some  extent,  since  the  pith  contains  reserve  food-material  in  the 
form  of  starch.  The  chief  effect  of  the  stem-borer  is,  however,  a 
mechanical  one.  The  stems  that  are  hollowed  out  fall  to  the  ground 
prematurely,  tho  not  until  they  have  attained  a  considerable  size.  One 
can  find  the  borers  most  abundantly  in  the  large  prostrate  stems  rather 
than  in  the  stems  that  remain  erect.  The  plants  that  lodge  carry 
their  flowers  to  the  ground,  become  soiled  with  dirt,  and  are  not  easy 
to  mow.  Mammoth  clover,  running  far  into  the  season,  lodges  badly 
from  the  work  of  the  borer;  while  medium  red  clover,  if  cut  when  it 
should  be,  escapes  practically  all  injury  from  this  insect. 

Rarely  the  borer  occurs  in  a  small  soft  stem  and  causes  it  to  wilt : 
for  in  such  a  stem  the  larva  eats  not  only  the  pith,  but  also  some  of 
the  adjacent  ducts,  thru  which  water  is  conveyed  up  the  stem  to  the 
leaves.  In  old  stems  these  ducts  are  too  tough  to  be  eaten  by  the 
larva. 

Were  this  insect  more  numerous  it  might  gradually  develop  into 
a  pest  of  considerable  importance.  It  is  most  common  on  clover,  but 
has  to  its  credit  the  fact  that  it  affects  also  a  considerable  number  of 
weeds. 

July  6  we  found  41  percent  of  the  old  stems  to  be  infested  by 
this  borer.  This  was  in  the  hay  crop — as  yet  uncut.  On  the  same 
day  we  examined  61  new  stems — the  second  growth  after  cutting — 
and  found  two  egg  pits  as  the  only  signs  of  the  borer.  The  beetles 


180 


BULLETIN  No.  134 


[April, 


had  disappeared,  almost  without  exception,  by  this  date.  July  7,  43 
percent  of  the  old  stems,  taken  from  many  different  places — roadside 
as  well  as  field — contained  the  insect. 

Stages. — The  beetle  (Fig.  23)  is  conspicuous  on  account  of  its 
slender  form,  dark  blue  wing-covers,  and  shiny  red  head  and  thorax. 
Length  4  mm.  to  7.8  mm.  In  Languria  mozardi,  as  distinguished  from 
other  species  of  the  genus,  the  antennae  are  black,  with  the  club  five- 
segmented;  the  legs  are  red,  with  the  outer  half  of  the  femur  black 
and  the  tibiae  and  tarsi  often  more  or  less  dusky;  last  three  abdominal 
segments  black,  the  abdomen  otherwise  red ;  elytra  rounded  at  apices, 
not  sinuate,  punctate-striate  with  the  interspaces  impunctate;  scutellum 
red ;  head  and  thorax  sparsely  punctate. 


FIG.  23. 


FIG.  24. 


Clover  Stem-borer,  Languria  mozardi:    Fig.  23,  beetle,  greatly  enlarged;   Fig.  24,  egg, 
in  natural  position,  four  times  natural  length. 

The  egg  (Fig.  24)  is  translucent  cream-yellow,  paler  at  each  end, 
elliptico-cylindrical  and  slightly  curving,  with  one  end  slightly  more 
tapering  than  the  other.  One  specimen  was  1.5  mm,  long  and  0.3  mm. 
broad  ;  another,  1.9  mm.  by  0.5  mm. 

The  larva  (Fig.  25)  is  slender,  subcylindrical,  8  mm.  long  and  0.9 
mm.  wide  when  full  grown,  and  light  yellow,  with  a  pair  of  brown 
curving  anal  hooks.  The  thoracic  legs  are  well  developed  and  there  is 
a  single  anal  proleg.  Comstock  gives  other  details.  At  birth  the  larva 
is  2  mm.  long;  when  four  days  old,  3  mm.;  nine  days,  5  mm.;  full 
grown,  as  above. 

The  pupa  (Fig.  26)  is  yellow,  slender,  has  a  large  head,  and  is  6 
mm.  long. 


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THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA 


181 


Life  History. — There  is  but  one  generation  a  year  in  this  latitude. 
Here  the  species  hibernates  as  a  beetle.  We  have  kept  it  alive  over 
winter.  It  may  also  winter  as  a  larva,  as  Chittenden  found  larvae 


FIG.  25. 


FIG.  26. 

Clover  Stem-borer,  Languria  mozardi:    Fig.  25,  larva;    Fig.  26,  pupa. 
Both   greatly  enlarged. 


remaining  as  such  from  November  to  April,  in  stems  of  ragweed.  In 
late  winter  and  early  spring  the  beetles  are  to  be  found  in  red-clover 
fields  under  the  rubbish  on  the  ground.  In  spring  they  eat  clover 
leaves  to  some  extent,  but  do  no  conspicuous  damage,  as  they  are 
comparatively  few.  In  May  and  June  these  beetles  mate;  by  July 
10,  nearly  all  of  them  have  died  off;  rarely  does  one  of  the  wintered 
beetles  survive  into  August.  Young  larvae  are  common  in  the  clover 
stems  in  the  last  week  of  June  and  early  in  July,  for  the  most  part ; 
tho  eggs  are  not  uncommon  early  in  July,  and  occur,  rarely,  as  late  as 
July  17.  Larvae  of  all  ages  are  common  in  clover  stems  in  July  and 
thereafter;  pupae  are  most  numerous  about  August  15;  and  the  beetles 
of  the  new  generation  emerge  from  the  first  of  August  up  to  the  mid- 
dle of  September,  if  not  later.  After  the  autumn  frosts  the  beetles 
are  to  be  found  on  the  ground  under  the  debris. 

Such  is  the  life  history,  in  condensed  form,  for  this  insect  in  this 
part  of  Illinois.  Some  details  of  importance  follow. 

Eggs  laid  May  19  hatched  May  24;  those  laid  July  14  hatched 
July  17.  The  egg  period  was  three  days  also  in  the  case  of  eggs 
that  hatched  July  8,  9,  and  10.  Eggs  were  taken  in  large  num- 
bers in  the  field  July  5,  6,  and  7,  at  which  time  20  percent  of  all  the 
large  clover  stems  examined  contained  each  an  egg.  In  one  field  41 
percent  of  the  clover  stems,  taken  at  random,  had  egg  pits  July  6,  with 
either  eggs  or  small  larvae  present. 


182  BULLETIN  No.  134  [April, 

Beetles  that  had  hibernated,  died  in  the  insectary  July  5,  9,  and 
26,  after  having  been  kept  there  with  proper  food,  etc.,  since  winter. 
By  July  5  most  of  the  beetles  are  gone  from  the  fields ;  only  a  few 
stragglers  continue  to  live,  there  being  a  conspicuous  break  between 
the  last  of  the  wintered  beetles  and  the  first  beetles  of  the  new  gen- 
eration. Larvae,  nearly  or  quite  grown,  and  pupae  are  common  in 
old  clover  stems  July  28  to  August  7.  About  July  30  the  larvae  are 
three  times  as  numerous  as  the  pupae;  but  after  the  first  week  in  Au- 
gust the  latter  exceed  the  former  in  number.  The  new  beetles  emerge 
mostly  thruout  August  and  during  the  first  half  of  September.  In 
the  insectary  they  issued  almost  every  day  from  August  3  to  Sep- 
tember 14,  and  one  emerged  September  20.  Most  of  them  have  is- 
sued by  August  26,  however.  At  that  date  the  burrows  are  almost  all 
vacant,  and  the  beetles  are  abroad  in  the  field,  feeding  a  little,  seeking 
shelter  at  every  cold  spell,  becoming  more  and  more  sluggish,  and 
finally  dormant.  Not  until  spring  does  the  reproductive  instinct 
awaken. 

Habits. — Oviposition  occurs  to  some  extent  late  in  May  and  early 
in  July,  but  for  the  most  part  in  June,  and  has  been  witnessed  in  the 
daytime.  The  female  gnaws  a  small  pit  on  the  stem  of  a  plant,  as 
Chittenden  and  others  have  observed.  On  clover  stems  these  pits  can 
be  found  easily.  Unless  freshly  made,  the  pit  is  brown,  in  contrast  to 
the  green  of  the  stem ;  a  pit  that  is  green  is  less  than  twenty- four  hours 
old,  and  indicates,  as  a  rule,  the  presence  of  an  egg.  The  egg-pit  is 
shallow,  oval  or  round  in  outline,  and  not  more  than  one  sixteenth  of 
an  inch  in  length.  In  the  center  of  the  pit  a  minute  linear  or  elliptic- 
al slit  opens  into  the  pith.  Upon  cutting  open  the  stem,  the  egg  is 
seen  on  the  inner  wall  of  the  stem,  often  opposite  the  pit,  but  sometimes 
as  far  from  it  as  four  to  six  millimeters.  The  female  makes  the  pit 
with  her  mandibles,  then  pushes  the  end  of  the  abdomen  thru  the  bot- 
tom of  the  pit  and  into  the  pith,  these  operations  taking  eight  minutes 
in  one  instance  and  sixteen  in  another,  as  observed  by  E.  O.  G.  Kelly. 
Sometimes  a  female  gnaws  out  a  pit  without  laying  the  egg.  In  red 
clover  the  eggs  are  laid  singly,  almost  invariably,  in  my  experience, 
rarely  two  being  found  together.  In  another  plant  (Leucanthemum} , 
however,  Mr.  Girault  saw  at  least  fifteen  eggs  deposited  in  the  same 
nidus  (Ent.  News,  Vol.  XVIIL,  pp.  366,  367). 

The  egg-pits  occur  on  the  main  stem  of  a  red  clover  plant  any- 
where from  three  to  twenty  inches  from  the  ground,  averaging  ten 
inches,  the  old  pits  having  been  carried  up  more  or  less  by  the  growth 
of  the  stem.  Fresh  pits,  especially  those  on  small  stems,  are  usually 
not  far  from  the  ground. 

The  larva,  feeding  on  the  pith  (Fig.  27),  tunnels  out  the  main  stem 
for  sometimes  two  feet.  If  two  larvae  occupy  the  same  stem  their 
combined  efforts  may  produce  a  burrow  as  long  as  thirty-two  inches, 
extending  from  the  main  stem  out  into  one  of  the  larger  branches. 
The  largest  larvae  and  the  pupae  (Fig.  28)  are  found  usually  at  the 
lower  end  of  the  burrow,  an  inch  or  two  from  the  ground,  the  pupa 


1909] 


THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA 


183 


with  the  head  upward.  The  beetle  (Fig.  29)  after  issuing  from  the 
pupa  lingers  in  the  burrow  for  a' while,  and  then  escapes  by  gnawing 
a  round  hole  straight  thru  the  wall  of  the  stem.  These  exit  openings 
are  rather  conspicuous. 


FIG.  27. 


FIG.  28. 


FIG.  29. 


Clover  Stem-borer,  Langiiria  mosardi:   Fig.   27,  larva,  in  clover  stem;  Fig.  28,  pupa,  in  same, — 
both  twice  natural  length;   Fig.  29,  beetle,   on  clover  stem,  slightly  enlarged. 

Natural  Enemies. — Comstock  mentioned  two  parasites  that  he 
found  in  the  burrows  of  this  stalk-borer :  a  small  black  chalcid,  with  a 
dark  naked  pupa;  and  a  yellowish  ichneumonid,  the  pupa  of  which  is 
enclosed  in  a  delicate  white  silken  cocoon.  C.  M.  Weed  gave  a  figure 
and  made  brief  mention  of  such  a  chalcid.  I  have  found  the  chalcid 
— probably  the  same  one — in  considerable  numbers  by  examining  an 
immense  number  of  stems.  The  egg  of  the  parasite  is  found  beside 
that  of  the  stem-borer,  and  hatches  a  little  later  than  the  latter  egg. 
The  chalcid  larva  bites  into  the  Languria  larva  and  feeds  upon  it  as  an 
external  parasite.  Now  and  then  the  chalcid  larva  detaches  itself 
from  its  host,  but  finds  the  latter  again  whenever  necessary.  The 
Languria  larva  dies;  the  parasite  survives  and  becomes  a  naked  pupa 
in  the  burrow,  from  which  the  adult  emerges  by  cutting  a  minute 
round  hole  thru  the  wall  of  the  stem. 

Eggs,  larvae,  and  pupae  of  the  parasite  were  most  frequent  in  the 
burrows  July  6  to  8.  The  adult  chalcids  issued  from  July  11  to  Au- 
gust 5, — most  numerously,  however,  in  the  last  week  of  July.  Au- 
gust 26  nearly  all  the  Languria  burrows  were  empty,  and  the  stems 
showed  the  exits  of  the  host  and  those  of  the  parasite. 

An  ichneumonid  cocoon  taken  in  a  Languria  burrow  by  me  Au- 
gust 7  gave  the  adult  August  11. 

Neither  of  these  species  has  been  determined. 


184  BULLETIN  No.  134  [April, 

Control. — The  clover  stem-borer  has  not  yet  attracted  much  at- 
tention as  an  injurious  insect.  Such  effects  as  it  produces  are  not  of 
the  violent  sort  which  attract  notice.  For  a  time  I  was  in  doubt  as  to 
whether  the  lodging  of  the  plants  was  due  in  any  degree  to  this  in- 
sect; later,  I  found  that  affected  stems  do  not  lodge  until  they  get 
large,  but  then  fall  sooner  than  unaffected  stems. 

Every  year  the  farmer  unknowingly  kills  off  large  numbers  of 
these  insects  when  he  cuts  his  hay  crop,  whether  he  cuts  it  early  or 
late,  for  in  the  latter  part  of  June  and  thruout  July  in  this  latitude 
the  great  majority  of  the  insects  are  inside  the  clover  stems  as  larvae 
or  pupse.  The  old  beetles  from  the  previous  year  are  practically  gone 
by  July  5,  and  the  new  beetles  do  not  issue  from  the  stems  until  about 
the  first  of  August.  If  the  cutting  of  the  hay  crop  is  neglected,  how- 
ever, and  left  far  into  July,  much  of  the  clover  will  be  flat  on  the 
ground  from  the  work  of  this  insect.  I  had  this  tested  on  the  uni- 
versity farm,  and  when  the  clover  was  cut,  heard,  from  the  man  who 
mowed  the  field,  certain  appropriate  comments  upon  the  amount  of 
clover  which  had  lodged. 

If  the  red  clover  is  cut  when  it  should  be — to  make  the  best  fod- 
der— only  about  three  stems  in  one  hundred  of  the  new  growth  will 
show  the  insect.  To  find  many  larvae  in  July  and  early  August  one 
has  to  search  in  uncut  field-clover,  or  in  clover  growing  wild  on  the 
border  of  a  field  or  by  the  side  of  the  road  or  the  railroad  track.  The 
practice  of  mowing  .and  destroying  volunteer  clover  is  well  worth  the 
little  time  that  it  takes. 

Languria  mozardi  Latr. 

1880.  Comstock,  J.  H.— Rep.    [U.  S.]    Comm.  Agr.,   1879,  pp. 

199,  200. 

1881.  Lintner,  J.  A.^Fortieth  Rep.  N.  Y.  State  Agr.  Soc.,  1880. 

pp.  18-20. 
1890.     Weed,  C.  M.— Amer.  Nat.,  Vol.  XXIV.,  p.  867. 

Weed,  C.  M.— Bull.  Ohio  Agr.  Exper.  Sta.,  Sec.  Ser.,  Vol. 

III.,  No.  8,  pp.  235-238. 
Chittenden,  F.  H.— Insect  Life,  Vol.  II.,  pp.  346,  347. 

CLOVER  SITONES 
Sit  ones  ftavescens  All. 

This  small  brown  curculio  eats  the  leaves  of  clovers  and  alfalfa, 
and  its  white  footless  grubs  feed  at  the  crown  or  at  the  roots  of  the 
same  plants.  It  has  rarely  been  reported  as  injurious  in  this  country, 
but  needs  to  be  watched,  nevertheless. 

The  species  is  abundant  in  the  Atlantic  states,  especially  near  the 
seashore,  is  on  record  from  Indiana,  Illinois,  Iowa,  and  Minnesota, 
and  doubtless  has  a  much  wider  distribution.  Everything  indicates 
that  it  came  from  Europe,  where  this  and  other  species  of  the  genus 
are  injurious  to  clover  and  lucerne  (alfalfa). 


1909] 


THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA 


185 


Food  Plants  and  Injuries. — White  clover,  alsike,  red  clover,  and 
alfalfa  are  known  to  be  eaten  freely  by  this  insect.  In  Europe 
another  food  plant  is  the  grass  Poa  annua.  Webster  found  a  strong 
preference  for  white  clover  and  alsike  over  red  clover  in  Indiana. 
Osborn  and  Gossard  found  red  clover  to  be  eaten  readily  in  Iowa. 
Here  in  Illinois  red  clover  is  commonly  eaten,  but  white  clover  shows 
rather  more  of  the  injury.  Alfalfa  is  also  eaten  to  some  extent.  The 
beetles  eat  at  the  edges  of  the  leaves,  and  the  larvae  feed  at  the  roots 
or  the  bases  of  the  stems. 

The  leaves  are  bitten  out  in  a  characteristic  manner,  on  acount  of 
the  methodical  feeding  habits  of  the  beetle.  On  an  expanded  leaflet 
the  beetle  eats  inward  from  the  margin,  making  a  small  hemispherical 
or  U-shaped  gap.  The  symmetrical  injury,  shown  in  Figure  30,  is,  how- 
ever, frequent,  as  the  beetle  often,  if  not  usually,  selects  a  young 
tender  leaflet  that  is  still  folded  in  halves  along  the  midrib,  and  notches 
out  both  margins  at  once ;  or  it  may  bite  out  a  hemispherical  notch  at 
the  midrib,  resulting  in  a  round  hole  when  the  leaflet  opens.  When 


FIG.  30. — Leaves  of  white  clover  showing 
characteristic  injury  by  beetle  of  Sitones 
ftavescens.  Natural  size. 

all  three  of  the  folded  leaflets  are  as 
yet  side  by  side,  the  beetle  at  one 
operation  produces  the  effect  shown 
in  the  leaf  at  the  left  in  Figure  30. 
A  single  notch  constitutes  a  meal, 
whether  the  beetle  happens  to  eat  one 
thickness  of  the  leaf  or  six. 

The  youngest  larvae  work  at  the 

bases  of  the  stems  or  the  bases  of  the  roots,  tho  most  of  the  injury  by 
them  is  done  on  the  roots.  .  A  few  of  these  larvae,  biting  out  the  roots 
near  the  crown,  can  cause  a  plant  to  wilt,  even  tho  no  other  insect  is 
present. 

Aside  from  the  serious  injury  done  to  white  clover  and  the  at- 
tacks upon  alsike  in  Indiana  in  1885,  as  reported  by  Webster,  this 
species  has  not  put  itself  on  record  as  an  injurious  insect  in  this 


FIG.  31. — Sitones  ftavescens.    Greatly 
enlarged. 


186  BULLETIN  No.  134  [April, 

country.  In  Europe,  however,  it  has  now  and  then  shown  what  it  is 
capable  of  doing  in  the  way  of  damage. 

Stages. — The  beetle  (Fig.  31)  is  a  small  dark  brown  or  rusty 
brown  curculio,  5.5  mm.  in  length,  with  the  beak  short  and  broad.  It 
is  distinguished  from  other  species  of  the  same  genus  by  the  absence 
of  erect  setae  on  the  interspaces  of  the  elytra,  and  by  its  minute,  nar- 
row, hairlike  scales.  On  fresh  specimens  the  pronotum  shows  a  pale 
median  dorsal  line  and  a  pale  stripe  on  each  side,  the  lateral  stripes 
being  continued  forward  on  the  head,  above  the  eyes,  and  along  the 
beak ;  and  also  backward  on  the  elytra  for  a  short  distance. 

In  the  genus  Sitones,  of  which  we  have  several  species  that  are 
potentially  injurious,  the  mandibles  are  stout,  convex  on  the  outside, 
and  roughly  punctured ;  and  the  antennal  grooves  extend  forward  to 
the  bases  of  the  mandibles, — not  to  mention  other  characters  given  by 
Le  Conte  and  Horn,  and  also  by  Casey.  As  in  other  Curculionidce,  the 
male  has  one  more  "dorsal  segment"  than  the  female,  owing  to  the 
division  of  the  pygidium  into  two  segments. 

The  egg  is  subspherical,  yellowish  white  at  first,  turning  greenish, 
and  becoming  black  in  two  or  three  days.  The  diameter  is  nearly  0.4 
mm.,  tho  the  egg  is  a  trifle  longer  than  broad. 

The  larva,  5  mm.  long  when  full  grown,  is  a  stout,  yellowish 
white,  footless  grub.  The  head  is  small  and  yellowish  brown,  with 
whitish  lines.  Body  segments  a  little  larger  than  the  head ;  the  second 
and  the  third  a  little  larger  than  the  first.  The  legs  are  represented  by 
fleshy  double  tubercles.  The  abdominal  segments  gradually  decrease 
in  size  and  bear  longer  hairs  than  the  thorax,  these  being  longest  on 
the  small  ninth  segment,  which  terminates  in  a  short,  stout,  truncate 
pseudopod. 

The  larvae  assume  a  hooklike  position,  as  mentioned  by  Webster, 
the  head  and  thorax  making  almost  a  right  angle  with  the  abdomen. 

The  pupa,  5  mm.  in  length,  is  pale  yellowish,  bearing  hairs, 
spinules,  and  tubercles.  The  abdomen  gradually  diminishes  in  size,  and 
the  segments  bear  a  few  short  reddish  spinules,  transversely  arranged ; 
the  ninth  segment  has  also  two  long,  slender,  converging  lateral  spines, 
whitish  basally  and  reddish  apically,  and  toothed  near  the  middle. 
The  pupa  and  the  larva  have  been  described  in  minute  detail  by 
Xambeu. 

Life  History. — Scarcely  anything  on  the  life  history  of  this  spe- 
cies has  appeared  in  our  literature  since  Webster's  useful  article  of 
twenty  years  ago.  In  central  Illinois  the  general  course  of  the  life 
history  is  markedly  like  that  of  the  clover  leaf-weevil.  There  is  one 
generation  each  year.  The  beetles  live  thru  summer  and  autumn,  and 
try  to  hibernate.  The  eggs  are  not  laid  until  late  in  the  season,  but 
they  hatch  in  the  same  season  and  the  little  larvae  hibernate. 

March  23  I  saw  the  characteristic  signs  of  the  beetle  on  one  red 
clover  leaf,  recently  expanded,  and  again  March  28,  on  white  clover. 
The  beetles  are  rare,  however,  in  spring,  and  the  earliest  record  that 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  187 

I  have  of  actually  finding  the  beetle  is  June  19.  This  may  have  been — 
and  probably  was — one  of  the  new  brood,  the  adults  of  which  are  not 
uncommon  in  the  last  week  of  June  and  become  common  by  the  middle 
of  July.  They  emerge  over  a  considerable  period,  as  our  records 
show,  our  dates  of  emergence  being  July  10  and  16,  and  August  20  and 
25.  The  pupal  period  is  two  to  three  weeks.  Thru  July,  Au- 
gust, and  September  the  beetles  are  common  in  the  field,  where  we 
have  found  them  as  late  as  October  8,  14,  and  31,  and  November  25; 
and  indoors,  they  may  be  kept  alive  far  into  the  winter  and  doubtless 
until  spring.  Like  the  clover  leaf-weevil,  these  other  curculios  feed 
for  a  long  time  before  mating  and  laying  eggs.  Dates  of  coition  are 
July  1  (exceptionally  early)  ;  August  26,  30,  and  31;  September  1,  8, 
10,  15,  and  27;  October  10,  18,  and  25;  and  November  14.  All  these 
records  except  those  of  September  8  and  10  were  made  in  the  insec- 
tary  (unheated  but  yet  affording  some  protection  from  frost),  and  out- 
of-doors  mating  and  oviposition  would  not  occur  for  quite  so  long  a 
time.  Two  to  ten  days  elapse  between  coition  and  egg-laying.  In 
the  field  most  of  the  eggs  are  laid  in  September.  Indoors  we  have 
found  them  to  have  been  laid  September  12,  14,  15,  19,  20,  22,  25,  26, 
27,  and  29;  October  23  and  27;  and  November  1,  2,  3,  4,  5,  10,  14,  16, 
17,  and  23.  For  several  years  we  have  kept  the  beetles  in  abundance 
under  daily  observation  thruout  their  long  lifetime,  without  getting 
other  dates  of  oviposition  than  these.  A  single  female  lays  her  eggs 
at  irregular  intervals  extending  over  several  weeks.  Thus  a  female 
which  copulated  October  25  laid  eggs  October  27,  November  2,  10,  17, 
and  24.  The  egg  period  varies,  even  under  conditions  apparently  the 
same,  and  ranges  from  13  to  32  days.  Hatching  occurred  in  the  in- 
sectary  from  October  17  to  November  29,  mostly  in  November,  and 
most  of  it  before  winter.  Not  a  few  eggs,  however,  failed  to  hatch  in 
autumn,  and  did  not  hatch  the  following  spring,  when  they  were 
evidently  dead.  There  remains,  nevertheless,  the  possibility  that  some 
eggs  survive  the  winter. 

The  species  winters  chiefly  as  a  young  larva,  but  occasionally  sur- 
vives as  a  beetle  in  this  region. 

Webster  dug  up  frozen  clover  sod  on  December  9,  at  Lafayette, 
Ind.,  and  found  therein,  after  thawing  it  out,  Sitones  larvae,  some  of 
them  1  mm.  long,  most  of  them  under  2.5  mm.  in  length,  and  two 
full  grown  and  in  earthen  cells.  He  found  also  two  beetles,  but  no 
pupae.  One  of  the  adults  was  still  alive  February  18.  April  13  he 
found  in  the  field,  larvae  (less  numerous  than  in  December,  and  in 
about  the  same  stage  of  growth),  no  pupae,  and  two  beetles,  which  died 
soon  afterward.  May  25  he  obtained  larvae  (less  numerous  than  in 
April,  but  now  nearly  or  quite  full-grown)  and  pupae,  and  a  single 
adult,  which  died  May  30.  These  beetles  laid  no  eggs.  June  14  he 
found  several  adults.  I  regard  these  as  belonging  to  the  new  brood. 

Webster's  account  serves  almost  exactly  for  the  species  as  it  oc- 
curs here  in  Urbana.  He  found,  however,  that  eggs  laid  October  17 
and  25  hatched  in  about  48  hours  at  a  temperature  of  65°  F. — a  much 


188  BULLETIN  No.  134  [April, 

shorter  period  than  any  that  we  have  as  yet  found.  He  notes  eggs  as 
being  laid  as  soon  as  August  7,  and  copulation  as  occurring  in  the  field 
as  late  as  November  12. 

Habits. — One  or  two  beetles  manage  to  live  over  winter,  and  even 
to  eat  a  little  in  early  spring.  Probably  they  issued  late  in  the  pre- 
vious season  and  had  enough  vitality  to  carry  them  over  to  the  next 
season.  I  do  not  believe  that  such  beetles  lay  any  eggs  in  spring,  how- 
ever, in  this  locality. 

When  the  larvae  emerge  from  the  egg  in  autumn  they  feed  on 
tender  green  tissue  down  where  the  stems  join,  avoiding  the  light  and 
biting  out  little  crevices,  in  which  they  lie.  As  it  gets  colder,  they 
go  down  deeper  and  reach  the  roots.  The  larger  larvae  and  the  pupae 
are  found  on  the  roots,,  and  part  of  the  eggs  are  laid  there,  some  of 
the  female  beetles,  after  copulation,  burrowing  down  along  the  roots. 
Other  females,  in  the  breeding-cage,  drop  their  eggs  promiscuously. 

The  beetles,  like  the  larvae,  avoid  bright  sunlight.  Most  of  them 
feed  by  night.  Some  feed,  to  be  sure,  in  the  daytime  when  the  sky  is 
overcast,  or  even  in  bright  daylight  on  a  shaded  portion  of  a  plant. 
To  find  many  of  the  beetles  during  the  day,  however,  one  must  scrape 
away  the  rubbish  on  the  ground  near  clover  plants  that  show  the 
characteristic  work  of  the  insect.  The  beetles  when  exposed  to  the 
light  are  quick  to  recover  their  wits,  and  to  hurry  off  to  another  shel- 
tered situation. 

The  beetle  when  engaged  in  feeding  stands  astride  upon  the  edge 
of  a  leaflet  and  stays  in  the  same  spot,  swinging  its  head  and  thorax 
up  and  down  as  it  eats,  and  biting  out  a  rounded  gap  always  of  about 
the  same  form  and  size.  The  beetles  are  alert  when  feeding,  and  drop 
to  the  ground  without  hesitation  when  approached  incautiously.  In- 
doors they  will  feed  in  the  daytime  if  the  light  is  not  too  strong. 

Control. — No  enemies  of  this  species  have  been  found  up  to  the 
present.  Should  it  become  destructive  it  would  be  hard  to  deal  with. 
The  cutting  of  the  hay  crop  has  little  or  no  effect  upon  the  larvae  or 
the  beetles;  the  former  continue  to  feed  on  the  roots,  and  the  latter 
feed  temporarily  on  the  green  stubble  and  attack  the  new  leaves  as 
soon  as  they  appear.  In  a  field  of  red  clover  cut  July  1,  I  found  the 
beetles  and  larvae  common  July  15 ;  on  clover  cut  July  23  the  new 
leaves  showed  considerable  injury  July  30. 

Fortunately  it  is  not  necessary  as  yet  to  prescribe  remedies  for 
the  attacks  of  this  weevil. 

Other  Species  of  Sitones. — In  Europe  several  species  of  Sitones 
are  injurious  to  clovers  and  allied  plants.  In  America  we  have  at  least 
four  of  the  European  species,  namely,  fiavescens,  tibialis,  hispidulus, 
and  lineellus.  Tibialis  is  of  no  economic  importance  here.  Hispidu- 
lus, according  to  Schwarz,  is  a  recent  importation.  It  was  first  no- 
ticed in  1876  in  New  Jersey,  and  subsequently  in  New  York,  Mary- 
land, and  Pennsylvania.  The  species  is  injurious  in  the  old  country 
and  may  become  a  pest  here.  Schwarz  found  it  to  be  abundant  in 
1889  in  Washington,  D.  C.,  feeding  on  red  clover. 


1909] 


THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA 


189 


Lineellus  is  another  potential  pest,  having  injured  clover  and 
alfalfa  in  Europe,  tho  it  is  not  common  here  as  yet.  In  Urbana,  it 
occurs  occasionally  in  red  clover  fields,  and  the  beetle  eats  the  leaves 
of  that  plant.  A  female  taken  November  26,  1907,  by  Mr.  R.  D. 
Glasgow,  a  student  at  the  University  of  Illinois,  was  kept  alive  on 
clover  leaves  for  a  long  time,  under  daily  observation,  and  laid 
eggs,  eight  being  found  November  27,  and  10  on  November  30.  These 
are  oval,  pale  translucent  yellow  when  laid,  becoming  jet-black;  sur- 
face minutely  granulate;  length,  0.5  mm.;  breadth,  0.38  mm.  Five  of 
the  eggs  found  November  27,  and  laid  not  before  November  26, 
hatched  December  16.  The  larva  at  hatching  is  white,  stout,  and 
footless,  with  a  black  head,  and  its  length  is  0.82  mm.  The  body  is 
wrinkled  to  such  an  extent  as  to  obscure  the  segmentation.  The  larva 
is  like  that  of  flavescens, 
and  bends  the  head  and 
thorax  over  in  the  same 
manner.  These  larvae 
fed  readi)y  on  red  clover, 
digging  into  the  bases  of 
roots  or  stems. 

To  these  few  but  new 
notes  on  the  life  history 
is  added  a  sketch  of  the 

newly  born  larva  Of  line-  FIG.    32.—  Larva     of     Sitones     lineellus     at     hatching. 

Greatly  enlarged. 


(Fig.  32). 

Sitones  flavescens  All. 

1887.  Webster,  F.  M.—  Rep.  [U.  S.]  Comm.  Agr.,  1886,  pp.  580- 
582. 

1890.  Schwarz,  E.  A.  —  Proc.  Ent.  Soc.  Washington,  Vol.  L,  pp. 

248-250. 

1891.  O  shorn,  H.,  and  Gossard,  H.  A.—  Bull.  No.  14,  Iowa  Agr. 

Exper.  Sta.,  pp.  177,  178. 

1896.  Xambeu.  —  Mceurs  et  Metam.  d'Insectes,  Mem.  5,  pp.  130- 
133;  Extr.,  Ann.  Soc.  Linn.  Lyon,  Vol.  XLIIL,  pp. 
152-155. 


CLOVER-ROOT  MEALY  BUG 

Pseudococcus  trifolii  Forbes 
(Coccus  trifolii,  Dactylopius  trifolii) 

This  root-feeding  mealy  bug  must  in  future  be  counted  among  the 
insects  that  kill  clover  plants.  Its  capacity  in  this  respect  has  been 
overlooked,  few  entomologists  having  paid  any  attention  to  this  incon- 
spicuous subterranean  species. 

The  insect  occurs  near  the  crown  of  the  plant,  as  a  plump  oval 
sluggish  mealy  bug,  with  more  or  less  of  a  white  coating.  It  sucks 
the  sap  of  ihe  root  by  means  of  a  minute  beak.  Legs  and  antennae 


190  BULLETIN  No.  134  [April, 

are  present,  but  are  very  small.  Almost  always  the  bugs  are  found  in 
groups  composed  of  individuals  of  various  sizes,  the  largest  being  2.5 
mm.  in  length.  Usually,  also,  these  mealy  bugs  are  accompanied  by 
ants. 

As  yet  we  know  of  the  presence  of  this  species  in  New  York, 
Delaware,  Illinois,  Michigan,  Iowa,  and  Kentucky  only,  but  may 
safely  assume  that  it  occurs  in  many  other  states. 

This  coccid  is  common  on  both  red  and  white  clover,  and  has 
been  reported  from  the  sugar-beet  by  R.  H.  Pettit. 

Tho  these  mealy  bugs  may  be  found  in  moderate  numbers  on  the 
roots  of  plants  that  appear  to  be  healthy,  the  easiest  way  to  find  them 
is  to  examine  clover  plants  that  are  more  or  less  wilted.  Unaided  by 
other  insects,  the  mealy  bug  often  kills  the  clover  plant.  At  first  a  few 
leaves  droop;  then  as  these  wilt  and  die  other  leaves  droop,  until 
finally  all  the  leaves  are  dead.  No  new  leaves  come  forth.  With 
sufficient  rain,  however,  the  plant  revives  if  not  too  far  gone.  On  the 
other  hand,  drought  intensifies  the  effect  of  this  sap-sucking  insect. 
Furthermore,  the  plant  may  suffer  at  the  same  time  from  the  root- 
borer,  the  leaf-weevil  or  the  clover-louse,  or  from  disease,  old  age, 
poor  soil,  overpasturage,  etc. 

A  certain  proportion  of  the  larvae  go  from  the  roots  to  the  leaves 
to  feed,  and  may  cause  the  leaves  to  turn  yellow  and  to  die. 

The  fact  that  the  injury  from  this  insect  is  not  wide-spread  is  ac- 
counted for  by  the  feeble  ability  of  the  wingless  females  to  go  from 
one  place  to  another,  and  the  habit  of  the  somewhat  more  active  larvae 
to  stay  on  the  same  plant.  I  have  never  found  the  species  on  first- 
year  red  clover,  tho  its  occasional  occurrence  on  such  clover  might  be 
expected ;  the  spread  of  the  insect  is  very  gradual ;  second-year  clover 
is  affected  in  a  sporadic  way,  except  in  a  few  localities  where  the  in- 
sect has  obtained  a  foothold;  and  the  worst  injury  is  done  to  clover, 
either  volunteer  or  cultivated,  that  has  run  for  more  than  two  years. 

Stages. — The  winter  female  was  described  by  Forbes  as  follows : 
"The  body  is  elliptical,  broadly  and  equally  rounded  at  both  ends, 
nearly  circular  in  transverse  vertical  section,  distinctly  segmented ; 
surface  covered  with  waxy  bloom,  smooth  except  for  a  few  small 
hairs  at  the  anal  extremity.  Feet,  eyes,  and  antennae  minute.  The 
body  is  .11  of  an  inch  long,  a  little  more  than  half  as  wide,  and  a  little 
less  than  half  as  deep ;  the  abdomen  decidedly  shorter  than  the  head 
and  thorax;  the  antennas  .006  of  an  inch  long,  their  length  less  than 
the  distance  between  their  bases,  obscurely  seven-jointed  [Fig.  33,  a]  ; 
the  first  joint  as  wide  as  long;  the  second  a  little  shorter  and  much 
narrower  than  the  first;  the  third  and  fourth  a  little  smaller  than  the 
second  and  not  distinctly  divided;  the  fifth  and  sixth  distinct,  equal 
in  length,  and  about  equal  to  the  first;  the  seventh  long,  cylindrical, 
equal  to  the  two  preceding,  obtusely  pointed  at  tip.  Entire  antenna 
minutely  sparsely  hairy  under  a  high  power.  Eyes  simple,  consisting 
of  a  single  ocellus  apd  a  black  speck  on  the  side  of  the  head,  directly 
behind  the  antenna,  the  third  joint  of  which  will  about  reach  them. 


1909] 


THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA 


191 


"Legs  .01  of  an  inch  in  length,  each  reaching  about  one  half  way 
to  its  fellow  of  the  opposite  side.  Tarsus  one-jointed,  as  long  as  the 
tibia,  tapering  regularly,  terminating  in  a  single  stout  curved  claw; 
tibia  and  femur  of  about  equal  length ;  trochanter  as  long  as  the  coxa. 
Legs  very  minutely  sparsely  hairy  throughout.  Rostrum  very  minute,  in 
the  form  of  a  thick  tubercle  projecting  downwards  in  front  of  the 
bases  of  the  anterior  legs,  scarcely  longer  than  wide,  about  half  the 
length  of  the  femur." 

I  may  add,  after  a  study  of  the  types,  that  the  bristle  of  each 
caudal  tubercle  (anal  lobe)  is  subtended  by  a  pair  of  conical  projec- 
tions (Fig.  34,  a)  ;  the  anal  ring  bears  six  long  bristles;  the  tarsal 
digitules  are  four  in  number  and  knobbed,  as  in  Figure  35 ;  and  the 
claw  bears  no  teeth.  The  largest  of  the  types  is  2.5  mm.  in  length. 


FIG.   33. — Antennae  of  Pseudococcus  trifolii:  a,  winter  female;   b,  summer  female; 
c,  larva.     Greatly  enlarged. 

The  summer  female  has  been  described  by  G.  C.  Davis  and  by  R. 
H.  Pettit.  The  latter  author  writes:  "The  adult  female  measures  a 
little  more  than  two  millimeters  in  length,  is  reddish  brown  in  color, 
covered  with  a  coating  of  waxy  or  mealy  secretion.  The  legs  are  dirty 
yellow  in  color.  From  the  sides  project  15  to  17  (usually  17)  waxy 
processes,  forming  a  fringe  around  the  body  in  the  usual  manner, 
with  the  shortest  filaments  near  the  head,  and  those  near  the  tail  con- 
siderably longer,  sometimes  one  third  as  long  as  the  body.  The  anten- 
nae [Fig.  33,  b]  are  eight-jointed;  joint  one  is  swollen,  as  broad  as 
long;  two  and  three  are  subequal,  each  about  as  long  as  one;  four,, 
five,  six  and  seven  subequal,  a  little  over  half  as  long  as  two  or  three; 
eight  usually  a  little  longer  than  five  and  six  joined.  There  is  consid- 
erable variation  in  four,  it  is  sometimes  smaller  than  five,  six  or 
seven,  and  sometimes  slightly  larger.  The  legs  are  dirty  yellow,  in 
length  the  tarsus  of  hind  leg  is  slightly  more  than  half  the  tibia,  which 
about  equals  the  femur.  Digitules  four;  the  two  superior  long  and 
slender,  the  two  inferior  shorter  and  more  stout.  (The  digitules  were 


192 


BULLETIN  No.  134 


[April, 


not  distinct,  but  appeared  as  described.)     Anal  tubercles  [Fig.  34,  b] 
not  prominent,  with  a  mass  of  small  glandular  spots,  and  bearing  one 

long  hair,  with  some- 
times several  smaller 
ones.  Among  the  gland- 

u^ar  sPots  are  place(i  two 
conical  projections  or 
processes  on  each  tuber- 
cle. These  processes  are 
from  two  to  three  times 
as  long  as  broad  at  the 
base.  Derm  dotted  with 
small  round  glandular 
,  spots.  Back,  near  the 

t>  caudal    margin,    spotted 

with  larger  round  gland- 


FiG.   34. — Caudal  region  of  Pseudococcus  trifolii:  a,  win- 
ter female;    b,  summer  female.     Greatly  enlarged. 


FIG.    35. — Foot   of  Pseudococcus 
trifolii.      Greatly   enlarged. 


ular  spots."  Digitules  and  claws  as  described  and  figured  by  the 
writer. 

The  larvae  derived  from  the  winter  females  are  from  0.69  mm.  to 
0.78  mm.  long  and  half  as  broad  as  long  at  birth,  and  are  elliptical 
and  flat,  looking  much  like  scale  insects.  The  antennae  are  six-seg- 
mented (Fig.  33,  c).  The  minute  structures  of  the  caudal  region  are 
essentially  like  those  of  the  adult  females,  as  in  Figure  34. 

The  male,  which  G.  C.  Davis  described,  is  a  minute  two-winged 
insect,  with  two  long  white  tail-filaments,  two  pairs  of  eyes,  delicate 
milky-white  wings,  and  the  body  thinly  covered  with  a  white  powder. 
The  head,  thorax,  and  first  two  antennal  segments  are  of  a  deeper  red 
than  the  abdomen,  legs,  and  remaining  antennal  segments.  The  eyes 
are  dark  reddish  brown.  A  mouth  is  not  evident. 

The  egg  is  elongate  oval,  0.34  mm.  long  and  0.17  mm.  broad, 
translucent  orange-yellow  at  first,  becoming  brownish  yellow  later, 
and  with  a  smooth  surface.  The  egg-mass  is  surrounded  by  the  cot- 
tony secretion  of  the  mother. 

The  winter  females  that  I  examined  all  had  seven  antennal  seg- 
ments ;  the  grown  larvae,  six ;  the  full-grown  summer  females,  eight ; 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  193 

partly  grown  larvae  show  the  stages  of  transition  from  six  to  eight 
segments.  In  young  larvae  the  division  between  segments  two  and 
three  is  frequently  obscure;  in  the  large  females  the  suture  between 
segments  two  and  three,  or  three  and  four,  is  obscure. 

Mr.  Pettit,  who  studied  summer  females,  intimated  that  the  win- 
ter specimens  from  which  the  original  description  was  made  were 
male  pupae.  A  study  of  the  types,  however,  has  shown  me  that  they 
are  females,  some  of  them  being  full  grown,  tho  they  resemble  the 
male  pupae  to  the  extent  of  having  only  seven  antennal  segments. 

The  necessity  for  using  the  name  Pseudococcus  for  the  genus 
formerly  called  Dactylopius  has  been  explained  by  Cockerell  (Ann. 
Mag.  Nat.  Hist.,  Ser.  7,  Vol.  IX.,  1902,  pp.  453,  454). 

Life  History. — The  first  account  of  this  coccid  was  given  by  Dr. 
Forbes,  who  found  the  species  on  the  roots  of  white  clover  May  3, 
at  Normal,  111.  He  found  that  the  coccids  "were  protected  by  a 
small  yellow  ant,  Lasius  ilavus,  in  whose  nests  they  occurred,  and 
were  carried  away  by  them  like  plant-lice  when  the  nest  was  exposed." 

The  general  course  of  the  life  history  has  been  made  known  by 
G.  C.  Davis  from  his  studies  in  Michigan.  He  found  the  coccids 
abundant  in  clover  fields  April  27,  and  attended  by  Lasius  niger. 
When  the  nests  of  the  ant  were  opened,  the  ants  carried  away  these 
coccids  to  another  location.  These  were  winter  females.  Davis  put 
some  of  them  on  potted  clover  and  obtained  young,  the  first  appear- 
ing May  15;  these  "gathered  under  the  mother  bug  or  collected  in 
the  flocculent  mass  back  of  her  that  she  had  secreted  while  producing 
them.  They  were  of  a  light,  translucent  flesh-color,  and  much  flatter 
than  the  mother." 

The  oviparous  female  makes  a  nest  of  waxy  threads  and  places 
therein  75  to  300  eggs.  "At  first  she  is  large  and  plump,  but,  as 
the  pile  of  eggs  increases,  she  decreases  in  size  until  at  last  there  is 
nothing  left  of  her  but  a  little  dry  wrinkled  piece  of  lifeless  skin,  and 
a  mass  of  eggs  back  of  her  that  will  measure  two  or  three  times  as 
much  as  she  did  a  short  time  before.  The  time  required  for  the  eggs 
to  hatch,  and  the  young  mealy  bugs  to  reach  maturity,  is  only  about 
six  or  seven  weeks." 

The  mealy  bugs,  tho  numerous  in  the  latter  part  of  summer,  dis- 
appear in  the  fall,  according  to  Davis,  who  failed  to  find  them  in  any 
stage  October  15  where  only  a  few  weeks  before  they  had  been  plen- 
tiful. He  suggested  that  they  had  changed  to  the  winter  form  and 
had  been  carried  off  by  the  ants. 

Davis  found  also  that  the  male,  when  about  half  or  a  third  the 
size  of  the  full-grown  female,  crawls  up  to  some  part  of  the  plant 
above  ground,  spins  a  fluffy  cocoon,  and  comes  out,  in  less  than  a 
week,  as  a  winged  adult. 

In  Urbana,  the  winter  females  of  various  sizes  occur  on  the  roots 
of  clover,  attended  by  ants,  in  early  spring.  Our  earliest  dates  are 
March  24  and  26,  but  the  females  could  doubtless  be  found  thruout 


194  BULLETIN  No.  134  [April, 

the  winter.  Small  winter  females  taken  March  28  and  placed  on  the 
roots  of  potted  clover  thrived  until  June  13,  then  disappeared. 

Of  the  young  brought  forth  on  the  roots  by  winter  females,  some 
stay  on  the  roots,  but  multitudes  at  once  climb  the  stem  of  the  plant 
and  fasten  themselves  by  the  beak  to  the  under  sides  of  the  leaves. 
These  oval,  flat,  green,  scalelike  larvae  may  stay  on  the  leaves  for  a 
month  or  a  little  longer,  growing  meanwhile,  or  may  go  to  the  ground 
sooner  than  that.  One  larva  taken  in  the  field  May  25  and  transferred 
to  potted  clover  stayed  on  the  leaves  until  June  5,  then  disappeared, 
to  reappear  June  9  down  on  the  stem  near  the  ground ;  there  it  re- 
mained until  June  27,  when  it  moulted ;  July  5  it  had  disappeared  for 
good. 

The  young  larvae  on  the  leaves  I  found  to  be  common  June  24, 
July  5,  and  July  8;  those  of  the  first  two  dates  were  newly  born  and 
had  not  moulted.  Larvae  on  leaves  June  24  were  transferred  to  the 
roots  July  30.  where  they  thrived  thruout  August. 

These  individuals  above  ground  wander  about  as  they  get  older, 
and  at  length  go  to  the  ground,  some  dropping  off  the  plant,  perhaps 
by  accident,  while  others  creep  down  the  stem  to  the  roots.  This 
migratory  habit  of  the  larvae  and  their  development  on  the  leaves 
have  not  heretofore  been  noted  apparently.  Very  likely  it  will  be 
found  that  these  aerial  females  are  fertilized  by  the  winged  males. 

While  these  individuals  are  feeding  on  the  leaves  there  are  others 
of  all  sizes  feeding  in  groups  on  the  roots;  in  fact,  the  root-feeding 
forms  can  probably  be  found  every  day  in  the  year.  The  number  of 
generations  has  not  been  made  out. 

No  eggs  have  been  found  in  spring,  and  in  our  experience  they 
are  not  laid  until  late  in  the  season.  Our  dates  for  oviposition  in  root- 
cages  are  August  31,  September  1,  2,  3,  5,  and  October  31.  We 
have  taken  eggs  in  the  field  August  31  and  September  15  and  27. 
The  eggs  always  hatched  before  winter,  the  egg  period  being  either  9 
or  10  days  in  September,  and  19  days  for  the  eggs  laid  October  31. 
The  dates  of  hatching  that  we  have  noted  are  September  1,  2,  5,  10, 
11,  12,  15,  18,  29,  and  November  19.  The  young  from  these  eggs  we 
have  carried  far  into  the  winter  on  clover  roots,  and  regard  them  as 
being  the  winter  females,  which  are  to  attain  their  full  growth  in 
spring.  ' 

Habits. — The  summer  females  wander  about  considerably  on  the 
roots  and  often  go  above  ground,  to  resume  feeding  at  the  base  of  the 
plant  in  some  crevice  protected  from  the  light,  where  they  often  lay 
eggs. 

As  met  with  in  the  field,  this  mealy  bug  is  almost  always  accom- 
panied by  ants,  which  have  made  their  nest  about  the  roots  of  the 
clover  plant.  The  species  of  ants  found  here,  in  this  relation,  are 
Lasius  flavus  DeG.,  as  mentioned  by  Forbes,  and  three  other  common 
species :  Lasius  niger  americanus  Mayr,  Lasius  inter jectus  Mayr,  and 
Myrmica  scabrinodis  lobicornis  Nyl. 


1909]  THE  INSECT  PESTS  OF  CLOVER  AND  ALFALFA  195 

This  coccid  can  get  along  very  well  without  the  ants,  however— 
unlike  the  corn  root-louse.  In  a  root-cage  the  ants  sometimes  desert 
the  coccids,  but  the  latter  continue  to  feed  and  to  produce  eggs  and 
young  as  tho  nothing  had  happened.  In  this  instance  the  ants  derive 
most  of  the  benefit  from  the  partnership.  When  an  ant  finds  one  of 
these  mealy  bugs  on  the  ground  or  on  the  base  of  a  plant,  the  ant 
picks  it  up  in  its  jaws,  carries  it  down  under  ground,  and  deposits  it 
somewhere  on  the  roots,  usually  not  far  from  the  base.  If  there  are 
eggs  with  the  female,  the  ants  carry  these  down  also  and  put  them  on 
rootlets. 

When  these  coccids  with  ants  and  their  cocoons  are  put  on  the 
surface  of  the  soil  in  a  root-cage,  the  ants  begin  by  burrowing  down 
along  the  roots.  Then  they  carry  down  the  coccids  and  the  cocoons. 
The  former  they  place  on  the  roots,  but  the  latter  they  carry  down 
deeper  to  special  chambers.  If  there  are  eggs  of  the  coccid,  the  ants 
show  many  attentions  to  them — touching  them  often  with  the  tips  of 
the  antennae,  carrying  them  from  place  to  place,  and  often  cleaning 
them  with  the  mouth — in  short,  treating  them  as  they  do  their  own 
eggs.  The  coccids  are  left  much  to  themselves,  but  occasionally  an 
ant  may  be  seen  eating  the  white  waxy  secretion  of  the  body  of  the 
female.  Mr.  E.  O.  G.  Kelly  says  that  this  secretion  is  eaten  only 
when  it  is  newly  made  and  fresh.  Much  of  it  is  left  by  the  ants  and 
is  used  by  the  female  to  cover  her  eggs. 

In  the  field  the  coccid  is  now  and  then  seen  above  ground  at  the 
base  of  a  plant  when  no  ants  are  present.  Occasionally,  also,  the 
coccids  are  found  working  on  the  roots  without  ants,  there  being 
either  no  sign  of  ants  or  else  a  nest  that  appears  to  be  deserted. 

This  coccid  spreads  very  slowly,  as  has  been  said.  Newly  born 
larvse  climb  the  stem  to  the  leaves,  but  seem  not  to  leave  the  plant  to 
any  great  extent,  tho  a  few  may  be  found  on  such  neighboring  plants 
as  are  easily  accessible.  The  summer  females  frequently  go  above 
ground  and  wander  about  a  little,  tho  they  are  sluggish.  Probably  the 
species  is  spread  by  ants  faster  and  farther  than  by  any  other  means. 

No  natural  enemies  of  this  mealy  bug  are  as  yet  known. 

Up  to  the  present  the  species  has  been  of  only  minor  economic 
importance. 

Pseudococcus  trifolii  Forbes. 

1885.     Forbes,  S.  A.— Fourteenth  Rep.  State  Ent.  111.,  pp.  72,  73. 
1890.     Carman,  H  —  Second  Rep.  Ky.  Agr.   Exper.  Sta.,  1889, 

pp.  19,  20. 
1894.     Davis,  G.  C— Insect  Life,  Vol.  VII.,  pp.  171-173. 

Davis,  G.  C. — Bull.  No.  116,  Mich.  Agr.  Exper.  Sta.,  pp. 

56-60. 

1899.     Pettit,  R.  H.— Can.  Ent.,  Vol.  XXXI.,  pp.  279,  280. 
1902.     Pettit,  R.  H.— Bull.  No.  200,  Mich.  Agr.  Exper.  Sta.,  pp. 

193,  194. 


196  BULLETIN  No.  134  [April, 


LITERATURE 

GENERAL  ARTICLES 

1881.  Lintner,  J.   A. — The  Insects  of  the  Clover  Plant.     Fortieth 

Ann.  Rep.  N.  Y.  State  Agr.  Soc.,  1880,  pp.  10-26.     Sep- 
arate, pp.  1-17. 

1882.  Saunders,  W. — Insects  Injurious  to  Clover.    Ann.  Rep.  Ent. 

Soc.  Ontario,  1881,  pp.  37^8. 

1894.  Davis,  G.  C— Insects  of  the  Clover  Field.  Bull.  No.  116,  Mich. 
Agr.  Exper.  Sta.,  pp.  41-64. 

1899.  Hunter,  W.  D. — A  Preliminary  Report  on  Insect  Enemies  of 
Clover  and  Alfalfa.  Ann.  Rep.  Neb.  State  Bd.  Agr.,  1898, 
pp.  239-285. 

1902.  Sanderson,  E.  D. — Insects  Injurious  to  Qover.  Insects  Inju- 
rious to  Staple  Crops,  pp.  172-187. 

LISTS  OF  SPECIES 

1881.     Lintner,  J.  A.— Fortieth  Ann.  Rep.  N.  Y.  State  Agr.  Soc.,  1880, 

pp.  13-15.    Separate,  pp.  4-6. 
1889.    Weed,  C.   M.— Bull.  No.   1,  Tech.  Sen,  Vol.   I.,  Ohio  Agr. 

Exper.  Sta.,  pp.  17-46. 
1896.     Cook,  A.  J.— W.  J.  Beal's  Grasses  of  North  America,  Vol.  I., 

pp.  370-395. 
1899,  1900.     Hunter,  W.  D.— Ann.  Rep.  Neb.  State  Bd.  Agr.,  1898, 

pp.  240-247;   1899,  p.  142. 


EXPLANATION  OF  PLATE  I. 

FIG.  1  to  3. — Clover  Seed-midge,  Dasyneura  leguminicola:  Fig.  1,  larva,  ventral 
aspect ;  2,  sternal  spatula ;  3,  female  midge.  All  greatly  enlarged. 

FIG.  4  to  8. — Clover  Leaf-midge,  Dasyneura  trifolii :  Fig.  4,  galls  on  white  clover, 
also  larvae  and  cocoons,  natural  size ;  5,  eggs ;  6,  larva,  dorsal  aspect ;  7, 
sternal  spatula ;  8,  female  midge.  Fig.  5  to  8  are  greatly  enlarged. 

FIG.  9  to  11. — Clover  Seed-caterpillar,  Enarmonia  interstinctana:  Fig.  9,  larva  at 
work  in  head  of  red  clover,  natural  size;  10,  larva,  enlarged;  11,  moth, 
enlarged. 


II 


7 


PLATE   I. 


1909] 


197 


PLATE   II. 

FIG.  1  to  4. — Clover-louse,  Macrosiphum  pisi:  Fig.  1,  winged  viviparous  female;  2,  wingless 
viviparous  female;  3,  aphid  attacked  by  fungus,  Empusa  aphidis;  4,  empty  skin  after 
emergence  of  parasite — Aphidius. 

FIG.  5  and  6. — Clover  Callipterus,  C,  trifolii:  Fig.  5,  wingless  viviparous  female;  6,  winged 
viviparous  female. 


JV/2 


